MIT News - Physicshttp://news.mit.edu/topic/mitphysics-rss.xml
MIT News is dedicated to communicating to the media and the public the news and achievements of the students, faculty, staff and the greater MIT community.enMon, 13 Aug 2018 11:00:00 -0400In neutron stars, protons may do the heavy liftinghttp://news.mit.edu/2018/neutron-stars-protons-may-do-heavy-lifting-0813
The positively charged particles may have an outsize influence on the properties of neutron stars and other neutron-rich objects.Mon, 13 Aug 2018 11:00:00 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/neutron-stars-protons-may-do-heavy-lifting-0813<p>Neutron stars are the smallest, densest stars in the universe, born out of the gravitational collapse of extremely massive stars. True to their name, neutron stars are composed almost entirely of neutrons — neutral subatomic particles that have been compressed into a small, incredibly dense celestial package.</p>
<p>A new study in <em>Nature, </em>co-led by MIT researchers<em>,</em> suggests that some properties of neutron stars may be influenced not only by their multitude of densely packed neutrons, but also by a substantially smaller fraction of protons — positively charged particles that make up just 5 percent of a neutron star.</p>
<p>Instead of gazing at the stars, the researchers came to their conclusion by analyzing the microscopic nuclei of atoms on Earth.</p>
<p>The nucleus of an atom is packed with protons and neutrons, though not quite as densely as in neutron stars. Occasionally, if they are close enough in distance, a proton and a neutron will pair up and streak through an atom’s nucleus with unusually high energy. Such “short-range correlations,” as they are known, can contribute significantly to the energy balance and overall properties of a given atomic nucleus.</p>
<p>The researchers looked for signs of proton and neutron pairs in atoms of carbon, aluminum, iron, and lead, each with a progressively higher ratio of neutrons to protons. They found that, as the relative number of neutrons in an atom increased, so did the probability that a proton would form an energetic pair. The likelihood that a neutron would pair up, however, stayed about the same. This trend suggests that, in objects with high densities of neutrons, the minority protons carry a disproportionally large part of the average energy.</p>
<p>“We think that when you have a neutron-rich nucleus, on average, the protons move faster than the neutrons, so in some sense, protons carry the action,” says study co-author Or Hen, assistant professor of physics at MIT. “We can only imagine what might happen in even more neutron-dense objects like neutron stars. Even though protons are the minority in the star, we think the minority rules. Protons seem to be very active, and we think they might determine several properties of the star.”</p>
<p><strong>Digging through data</strong></p>
<p>Hen and his colleagues based their study on data collected by CLAS — the CEBAF (Continuous Electron Beam Accelerator Facility) Large Acceptance Spectrometer, a particle accelerator and detector based at Jefferson Laboratory in Virginia. CLAS, which operated from 1998 to 2012, was designed to detect and record the multiple particles that are emitted when beams of electrons impinge on atomic targets.</p>
<p>“Having this property of a detector that sees everything and also keeps everything for offline analysis is extremely rare,” Hen says. “It even has kept what people considered ‘noise,’ and we’re now learning that one person’s noise is another person’s signal.”</p>
<p>The team chose to mine CLAF’s archived data for signs of short-range correlations — interactions that the detector was not necessarily meant to produce, but that it captured nonetheless.</p>
<p>“People were using the detector to look at specific interactions, but meanwhile, it also measured in parallel a bunch of other reactions that took place,” says collaborator Larry Weinstein, a professor of physics at Old Dominion University. “So we thought, ‘Let’s dig into this data and see if there’s anything interesting there.’ We want to squeeze as much science as we can out of experiments that have already run.”</p>
<p><strong>A full dance card</strong></p>
<p>The team chose to mine CLAS data collected in 2004, during an experiment in which the detector aimed beams of electrons at carbon, aluminum, iron, and lead atoms, with the goal of observing how particles produced in nuclear interactions travel through each atom’s respectively larger volume. Along with their varying sizes, each of the four types of atoms have different ratios of neutrons to protons in their nuclei, with carbon having the fewest neutrons and lead having the most.</p>
<p>The reanalysis of the data was done by graduate student Meytal Duer from Tel Aviv University in a collaboration with MIT and Old Dominion University, and was led by Hen. The overall study was conducted by an international consortium called the CLAS Collaboration, made up of 182 members from 42 institutions in 9 countries.</p>
<p>The group studied the data for signs of high-energy protons and neutrons — indications that the particles had paired up — and whether the probability of this pairing changed as the ratio of neutrons to protons increased.</p>
<p>“We wanted to start from a symmetric nucleus and see, as we add more neutrons, how things evolve,” Hen says. “We would never get to the symmetries of neutron stars here on Earth, but we could at least see some trend and understand from that, what could be going on in the star.”&nbsp;</p>
<p>In the end, the team observed that as the number of neutrons in an atom’s nucleus increased, the probability of protons having high energies (and having paired up with a neutron) also increased significantly, while the same probability for neutrons remained the same.</p>
<p>“The analogy we like to give is that it’s like going to a dance party,” Hen says, invoking a scenario in which boys who might pair up with girls on the dance floor are vastly outnumbered. “What would happen is, the average boy would … dance a lot more, so even though they were a minority in the party, the boys, like the protons, would be extremely active.”</p>
<p>Hen says this trend of energetic protons in neutron-rich atoms may extend to even more neutron-dense objects, such as neutron stars. The role of protons in these extreme objects may then be more significant than people previously suspected. This revelation, Hen says, may shake up scientists’ understanding of how neutron stars behave. For instance, as protons may carry substantially more energy than previously thought, they may contribute to properties of a neutron star such as its stiffness, its ratio of mass to size, and its process of cooling.</p>
<p>“All these properties then affect how two neutron stars merge together, which we think is one of the main processes in the universe that create nuclei heavier than iron, such as gold,” Hen says. “Now that we know the small fraction of protons in the star are very highly correlated, we will have to rethink how [neutron stars] behave.”</p>
<p>This research was supported, in part, by the U.S. Department of Energy, the National Science Foundation, the Israel Science Foundation, the Chilean Comisión Nacional de Investigación Científica y Tecnológica, the French Centre National de la Recherche Scientifique and Commissariat a l’Energie Atomique, the French-American Cultural Exchange, the Italian Istituto Nazionale di Fisica Nucleare, the National Research Foundation of Korea, and the UK’s Science and Technology Facilities Council.</p>
MIT researchers used archived data from the CLAS detector to study interactions in neutron-rich atoms.Courtesy of the researchersAstronomy, Astrophysics, Laboratory for Nuclear Science, Nuclear science and engineering, Physics, Research, School of Science, Department of Energy (DoE), National Science Foundation (NSF)3Q: A bold mission to touch the sunhttp://news.mit.edu/2018/3q-john-belcher-parker-solar-probe-0813
MIT’s John Belcher discusses the launch of the Parker Solar Probe, which will fly directly into the sun’s atmosphere.Mon, 13 Aug 2018 00:00:00 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/3q-john-belcher-parker-solar-probe-0813<p><em>On Sunday, NASA launched a bold mission to fly directly into the sun’s atmosphere, with a spacecraft named the <a href="https://www.nasa.gov/content/goddard/parker-solar-probe">Parker Solar Probe</a>, after solar astrophysicist Eugene Parker. The incredibly resilient vessel, vaguely shaped like a lightbulb the size of a small car, was launched early in the morning from Cape Canaveral Air Force Station in Florida. Its trajectory will aim straight for the sun, where the probe will come closer to the solar surface than any other spacecraft in history. </em></p>
<p><em>The probe will orbit the blistering corona, withstanding unprecedented levels of radiation and heat, in order to beam back to Earth data on the sun’s activity. Scientists hope such data will illuminate the physics of stellar behavior. The data will also help to answer questions about how the sun’s winds, eruptions, and flares shape weather in space, and how that activity may affect life on Earth, along with astronauts and satellites in space. </em></p>
<p><em>Several researchers from MIT are collaborating on the mission, including co-principal investigators John Belcher, the Class of 1992 Professor of Physics, and John Richardson, a principal research scientist in MIT’s Kavli Institute for Astrophysics and Space Research. </em>MIT News<em> spoke with Belcher about the historic mission and its roots at the Institute.</em></p>
<p><strong>Q:</strong> This has to be one extreme vehicle to withstand the sun’s radiation at such close range. What kind of effects will the probe experience as it orbits the sun, and what about the spacecraft will help it stay on course?</p>
<p><strong>A:</strong> The spacecraft will come as close as 3.9 million miles to the sun, well within the orbit of Mercury and more than seven times closer than any spacecraft has come before. This distance is about 8.5 solar radii, very close to the region where the solar wind is accelerated.&nbsp;At these distances the sun will be over 500 times brighter than it appears to Earth, and particle radiation from solar activity will be harsh.</p>
<p>In order to survive, the spacecraft folds its solar panels into the shadows of its protective solar shade, leaving just enough of the specially angled panels in sunlight to provide power closer to the sun.&nbsp;To perform these unprecedented investigations, the spacecraft and instruments will be protected from the sun’s heat by a 4.5-inch-thick carbon-composite shield, which will need to withstand temperatures outside the spacecraft that reach nearly 2,500 degrees Fahrenheit.&nbsp;</p>
<p><strong>Q:</strong> What data will the probe be collecting, and what insights are scientists ultimately hoping to gain from these data?</p>
<p><strong>A:</strong> There will be a variety of instruments to measure solar particles and fields near the sun, including a low-energy plasma instrument, a magnetometer, and a suite of energetic particle instruments. These will help determine the structure and dynamics of the magnetic fields at the sources of solar wind, trace the flow of energy that heats the corona and accelerates the solar wind, and determine what mechanisms accelerate and transport energetic particles.&nbsp;</p>
<p>The acceleration of the solar wind is still an outstanding question, mostly because all of the acceleration is over by [the time the wind has traveled] 25 solar radii. The Earth sits at 215 solar radii, so we have never made the most crucial observations close to the sun.&nbsp;It is only by getting this close to the sun that we have a chance of answering definitely what accelerates the wind.&nbsp;The major question is whether thermal processes or wave acceleration processes are most important, or both.&nbsp;&nbsp;</p>
<p><strong>Q:</strong> What is MIT’s role in this endeavor?&nbsp;&nbsp;</p>
<p><br />
<strong>A:</strong> John Richardson and I are co-investigators on the Solar Wind Electrons Alphas and Protons (SWEAP) Investigation for the mission. The principal investigator, Professor Justin Kasper of the University of Michigan, is an MIT graduate and was trained by Alan Lazarus, working on the Faraday cup launched on the DSCOVR satellite in 2014.</p>
<p>The SWEAP Investigation is the set of instruments on the spacecraft that will directly measure the properties of the plasma in the solar atmosphere during these encounters. A special component of SWEAP is a small instrument that will look around the protective heat shield of the spacecraft directly at the sun, the only instrument on the spacecraft to do so. This will allow SWEAP to sweep up a sample of the atmosphere of the sun, our star, for the first time at these distances.</p>
<p>This small instrument looking around the heat shield is a <a href="https://en.wikipedia.org/wiki/Faraday_cup">Faraday cup</a>, and is a direct descendant of the first instrument to measure the existence of the supersonic solar wind expansion.&nbsp; That measurement was carried out by Professor Herb Bridge, Dr. Al Lazarus, and Professor Bruno Rossi, [all of MIT], on Explorer 10 in 1961.</p>
<p>At the same time the solar probe Faraday cup is measuring the properties of the solar wind close to the sun at 8 solar radii, a sister Faraday cup on Voyager (launched in 1977) will probably be measuring plasma in the local interstellar space, totally outside the solar atmosphere, beyond 100 astronomical units, or 20,000 solar radii. This Voyager 2 instrument has been in space for more than 40 years, consistently returning data to Earth. Thus two probes which trace their lineage to MIT Professor Herb Bridge will be making measurements at opposite ends of the solar system, from as close as you can get to the sun to as far away as the local interstellar medium.&nbsp;</p>
Illustration of NASA's Parker Solar Probe in front of the Sun.Image: NASA/Johns Hopkins APL/Steve GribbenAeronautical and astronautical engineering, NASA, Satellites, Physics, Planetary science, Research, School of Science, Solar, space, Space, astronomy and planetary science, 3 Questions, Kavli InstitutePaying it forward: Fellowship boosts women in physicshttp://news.mit.edu/2018/paying-it-forward-fellowship-boosts-women-physics-0802
Four students are first beneficiaries of grant program established by Assistant Professor Lindley Winslow with support from the Heising-Simons Foundation.Thu, 02 Aug 2018 13:40:01 -0400Sandi Miller | Department of Physicshttp://news.mit.edu/2018/paying-it-forward-fellowship-boosts-women-physics-0802<p>There’s no doubt that in order to study physics, students must be first-rate learners. But another essential skill that may not be so obvious is the ability to craft a great research proposal, which is key to career advancement.</p>
<p>Early in her career, <a href="http://web.mit.edu/physics/people/faculty/winslow_lindley.html">Lindley Winslow</a>, the Jerrold R. Zacharias Career Development Assistant Professor of Physics at MIT, received mentorship that was crucial to her career path. She is now paying it forward with the launch of a <a href="https://physicsresearchfellows.mit.edu/">physics research fellowship</a> program to help undergrads, graduate students, and postdocs in the Department of Physics, especially within a particularly underrepresented group: female physicists.</p>
<p>Winslow’s pilot program not only offers money for research, but also builds in a workshop on preparing research proposals. “The program is more than just how to write a proposal,” said Winslow. “It is designing a self-contained research project and then writing the supporting research proposal. It is putting together the idea, budget, and timeline as well as the text.”</p>
<p>Winslow says while the program is open to all, it is aimed at women because at MIT alone, women make up only 22 percent of physics students, and 15 percent of physics faculty, if you include adjuncts and secondary appointments. In the hopes of increasing these numbers, Winslow received a $75,000 grant from the <a href="https://www.hsfoundation.org/about/">Heising-Simons Foundation</a> to fund a program aimed at helping women in physics.</p>
<p>The heart of the program is to provide support on the research grant process, with guidelines of $5,000 for undergraduate projects, $10,000 for graduate student projects, and $15,000 for postdoctoral projects. Funds are expected to be used for non-stipend expenses including equipment, materials, supplies,&nbsp;computers, and travel for collaboration and scientific meetings. The proposals will be peer-reviewed in the National Science Foundation style, with Winslow acting as the program manager.</p>
<p>Winslow received 16 fellowship applications by the May deadline, and four were chosen. The first round of fellows selected are Clara Sousa-Silva, who is working on "Creating a Rosetta Stone for the Interpretation of Exoplanet Biospheres" with mentor Professor Sara Seager; Shuo Zhang, for her project "Probing MeV-GeV Cosmic-ray Particles in the Galactic Center," with Professor Kerstin Perez; Carina Belvin, for her project, "Investigating Nonequilibrium Magnetization Dynamics Using Ultrafast Terahertz Spectroscopy," under Professor Nuh Gedik; and Radha&nbsp;Mastandrea, for her project "Analyzing CMS Open Collider Data Though Machine Learning," with Professor Jesse Thaler.</p>
<p>The second round of proposals are <a href="https://physicsresearchfellows.mit.edu/">due Dec. 7</a>.</p>
<p>Winslow, an experimental nuclear physicist whose primary focus is on neutrinoless double-beta decay, modeled the fellowship on the 2010 $60,000 L’Oreal for Women in Science Fellowship that she earned while an MIT postdoc, which was from 2008 to 2012.</p>
<p>“I have been very lucky that I have had very strong mentoring, which I credit to my current success: My thesis advisor, who used the classical approach of having us contribute to the writing of the group grant, and my colleague at UCLA, who proofread my NSF CAREER proposal and told me I needed to make sure the big picture was front and center.”</p>
<p>It was her postdoc advisor, Professor <a href="http://web.mit.edu/physics/people/faculty/conrad_janet.html">Janet Conrad</a>, who mentored Winslow on how to create a good proposal. “She took a very detailed approach of breaking down what is a good proposal, how to construct it, how to work with your program manager to tailor the budget and subject, and finally to deliver something that will be reviewed well by your peers,” said Winslow. “She was responsible for me applying to the L’Oreal and helped me re-write, refine, and edit that proposal (and a couple others since then).”</p>
<p>Winslow never forgot the importance of mentorship. In 2016, she was among a dozen leading scholars in physics and astronomy at a Heising-Simons Foundation summit that discussed academic and career pathways for women in these fields. She was also on the workshop committee for a separate Heising-Simons initiative at April’s <a href="https://physicsrisingstars.mit.edu/">Rising Stars in Physics Workshop</a>, for women interested in navigating the early stages of academic careers in physics and astronomy.</p>
<p>At a kickoff event for the new fellowship, Winslow surveyed Women in Physics group members and discovered that few students knew much about the grant proposal process. “It was striking how confident they were that they could execute a research plan, but how that confidence disappeared when I asked about their ability to come up with ideas and actually prepare the proposal,” Winslow recalled.</p>
<p>To ensure their success, workshops trained applicants on how to put their best foot forward. “This program aims to “pull back the curtain” and teach our students and postdocs how that part of the system works,” says Winslow.</p>
<p>“The process of structuring projects and writing grants to support them is one of the most intimidating aspects of the academic path, and is a particular barrier for women. It’s these sorts of tasks — qualifying exams, physics GREs, job applications — that end up affecting women more due to a combination of confidence, unequal mentoring, and societal pressure. Confidence in your ability to get grants is integral to wanting to stay in the field, and the numbers (of women physicists) are so low that we cannot afford to lose anyone.”</p>
Recipients of a grant from the Heising-Simons Foundation are (l-r) Radha Mastandrea, Carina Belvin, and Shuo Zhang. Professor Lindley Winslow, who established the grant program, is at right. Not pictured: grant recipient Clara Sousa-Silva.Photo: Sandi MillerAwards, honors and fellowships, Grants, Funding, Physics, Women in STEM, Diversity and inclusion, School of ScienceOn-chip optical filter processes wide range of light wavelengthshttp://news.mit.edu/2018/chip-optical-filter-processes-wide-range-light-wavelengths-0801
Silicon-based system offers smaller, cheaper alternative to other “broadband” filters; could improve a variety of photonic devices.Wed, 01 Aug 2018 04:59:59 -0400Rob Matheson' | MIT News Officehttp://news.mit.edu/2018/chip-optical-filter-processes-wide-range-light-wavelengths-0801<p>MIT researchers have designed an optical filter on a chip that can process optical signals from across an extremely wide spectrum of light at once, something never before available to integrated optics systems that process data using light. The technology may offer greater precision and flexibility for designing optical communication and sensor systems, studying photons and other particles through ultrafast techniques, and in other applications.</p>
<p>Optical filters are used to separate one light source into two separate outputs: one reflects unwanted wavelengths — or colors — and the other transmits desired wavelengths. Instruments that require infrared radiation, for instance, will use optical filters to remove any visible light and get cleaner infrared signals.</p>
<p>Existing optical filters, however, have tradeoffs and disadvantages. Discrete (off-chip) “broadband” filters, called dichroic filters, process wide portions of the light spectrum but are large, can be expensive, and require many layers of optical coatings that reflect certain wavelengths. Integrated filters can be produced in large quantities inexpensively, but they typically cover a very narrow band of the spectrum, so many must be combined to efficiently and selectively filter larger portions of the spectrum.</p>
<p>Researchers from MIT’s Research Laboratory of Electronics have designed the first on-chip filter that, essentially, matches the broadband coverage and precision performance of the bulky filters but can be manufactured using traditional silicon-chip fabrication methods.</p>
<p>“This new filter takes an extremely broad range of wavelengths within its bandwidth as input and efficiently separates it into two output signals, regardless of exactly how wide or at what wavelength the input is. That capability didn’t exist before in integrated optics,” says Emir Salih Magden, a former PhD student in MIT’s Department of Electrical Engineering and Computer Science (EECS) and first author on a paper describing the filters published today in <em>Nature Communications</em>.</p>
<p>Paper co-authors along with Magden, who is now an assistant professor of electrical engineering at Koç University in Turkey, are: Nanxi Li, a Harvard University graduate student; and, from MIT, graduate student Manan Raval; former graduate student Christopher V. Poulton; former postdoc Alfonso Ruocco; postdoc associate Neetesh Singh; former research scientist Diedrik Vermeulen; Erich Ippen, the Elihu Thomson Professor in EECS and the Department of Physics; Leslie Kolodziejski, a professor in EECS; and Michael Watts, an associate professor in EECS.</p>
<p><strong>Dictating the flow of light</strong></p>
<p>The MIT researchers designed a novel chip architecture that mimics dichroic filters in many ways. They created two sections of precisely sized and aligned (down to the nanometer) silicon waveguides that coax different wavelengths into different outputs.</p>
<p>Waveguides have rectangular cross-sections typically made of a “core” of high-index material — meaning light travels slowly through it — surrounded by a lower-index material. When light encounters the higher- and lower-index materials, it tends to bounce toward the higher-index material. Thus, in the waveguide light becomes trapped in, and travels along, the core.</p>
<p>The MIT researchers use waveguides to precisely guide the light input to the corresponding signal outputs. One section of the researchers’ filter contains an array of three waveguides, while the other section contains one waveguide that’s slightly wider than any of the three individual ones.</p>
<p>In a device using the same material for all waveguides, light tends to travel along the widest waveguide. By tweaking the widths in the array of three waveguides and gaps between them, the researchers make them appear as a single wider waveguide, but only to light with longer wavelengths. Wavelengths are measured in nanometers, and adjusting these waveguide metrics creates a “cutoff,” meaning the precise nanometer of wavelength above which light will “see” the array of three waveguides as a single one.</p>
<p>In the paper, for instance, the researchers created a single waveguide measuring 318 nanometers, and three separate waveguides measuring 250 nanometers each with gaps of 100 nanometers in between. This corresponded to a cutoff of around 1,540 nanometers, which is in the infrared region. When a light beam entered the filter, wavelengths measuring less than 1,540 nanometers could detect one wide waveguide on one side and three narrower waveguides on the other. Those wavelengths move along the wider waveguide. Wavelengths longer than 1,540 nanometers, however, can’t detect spaces between three separate waveguides. Instead, they detect a massive waveguide wider than the single waveguide, so move toward the three waveguides.</p>
<p>“That these long wavelengths are unable to distinguish these gaps, and see them as a single waveguide, is half of the puzzle. The other half is designing efficient transitions for routing light through these waveguides toward the outputs,” Magden says.</p>
<p>The design also allows for a very sharp roll-off, measured by how precisely a filter splits an input near the cutoff. If the roll-off is gradual, some desired transmission signal goes into the undesired output. Sharper roll-off produces a cleaner signal filtered with minimal loss. In measurements, the researchers found their filters offer about 10 to 70 times sharper roll-offs than other broadband filters.</p>
<p>As a final component, the researchers provided guidelines for exact widths and gaps of the waveguides needed to achieve different cutoffs for different wavelengths. In that way, the filters are highly customizable to work at any wavelength range. “Once you choose what materials to use, you can determine the necessary waveguide dimensions and design a similar filter for your own platform,” Magden says.</p>
<p><strong>Sharper tools</strong></p>
<p>Many of these broadband filters can be implemented within one system to flexibly process signals from across the entire optical spectrum, including splitting and combing signals from multiple inputs into multiple outputs.</p>
<p>This could pave the way for sharper “optical combs,” a relatively new invention consisting of uniformly spaced femtosecond (one quadrillionth of a second) pulses of light from across the visible light spectrum — with some spanning ultraviolet and infrared zones — resulting in thousands of individual lines of radio-frequency signals that resemble “teeth” of a comb. Broadband optical filters are critical in combining different parts of the comb, which reduces unwanted signal noise and produces very fine comb teeth at exact wavelengths.</p>
<p>Because the speed of light is known and constant, the teeth of the comb can be used like a ruler to measure light emitted or reflected by objects for various purposes. A promising new application for the combs is powering “optical clocks” for GPS satellites that could potentially pinpoint a cellphone user’s location down to the centimeter or even help better detect gravitational waves. GPS works by tracking the time it takes a signal to travel from a satellite to the user’s phone. Other applications include high-precision spectroscopy, enabled by stable optical combs combining different portions of the optical spectrum into one beam, to study the optical signatures of atoms, ions, and other particles.</p>
<p>In these applications and others, it’s helpful to have filters that cover broad, and vastly different, portions of the optical spectrum on one device.</p>
<p>“Once we have really precise clocks with sharp optical and radio-frequency signals, you can get more accurate positioning and navigation, better receptor quality, and, with spectroscopy, get access to phenomena you couldn’t measure before,” Magden says.</p>
<p>The new device could be useful, for instance, for sharper signals in fiber-to-the-home installations, which connect optical fiber from a central point directly to homes and buildings, says Wim Bogaerts, a professor of silicon photonics at Ghent University. “I like the concept, because it should be very flexible in terms of design,” he says. “It looks like an interesting combination of ‘dispersion engineering’ [a technique for controlling light based on wavelength] and an adiabatic coupler [a tool that splits light between waveguides] to make separation filter for high and low wavelengths.”</p>
MIT researchers have designed an optical filter on a chip that can process optical signals from across an extremely wide spectrum of light at once, something never before available to integrated optics systems that process data using light.Image: E. Salih MagdenResearch, Photonics, Manufacturing, Nanoscience and nanotechnology, Research Laboratory of Electronics, Electrical Engineering & Computer Science (eecs), Physics, School of Engineering, School of Science3Q: Richard Milner on a new U.S. particle acceleratorhttp://news.mit.edu/2018/3q-richard-milner-new-us-particle-accelerator-0724
Proposal for powerful particle collider gets National Academies’ go-ahead.Tue, 24 Jul 2018 14:52:33 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/3q-richard-milner-new-us-particle-accelerator-0724<p><em>The case for an ambitious new particle accelerator to be built in the United States has just gotten a major boost. </em></p>
<p><em>Today, the National Academies of Sciences, Engineering, and Medicine have endorsed the development of the Electron Ion Collider, or EIC. The proposed facility, consisting of two intersecting accelerators, would smash together beams of protons and electrons traveling at nearly the speed of light. In the aftermath of each collision, scientists should see “snapshots” of the particles’ inner structures, much like a CT scan for atoms. From these images, scientists hope to piece together a multidimensional picture, with unprecedented depth and clarity, of the quarks and gluons that bind together protons and all the visible matter in the universe. </em></p>
<p><em>The EIC, if built, would significantly advance the field of quantum chromodynamics, which seeks to answer fundamental questions in physics, such as how quarks and gluons produce the strong force — the “glue” that holds all matter together. If constructed, the EIC would be the largest accelerator facility in the U.S. and, worldwide, second only to the Large Hadron Collider at CERN. MIT physicists, including Richard Milner, professor of physics at MIT, have been involved from the beginning in making the case for the EIC. </em></p>
<p>MIT News<em> checked in with Milner, a member of the Laboratory for Nuclear Science, about the need for a new particle collider and its prospects going forward. &nbsp;&nbsp;</em></p>
<p><strong>Q:</strong> Tell us a bit about the history of this design. What has it taken to make the case for this new particle accelerator?</p>
<p><strong>A:</strong> The development of both the scientific and technical case for the EIC has been in progress for about two decades. With the development of quantum chromodynamics (QCD) in the 1970s by MIT physics Professor Frank Wilczek and others, nuclear physicists have long sought to bridge the gap between QCD and the successful theory of nuclei based on experimentally observable particles, where the fundamental constituents are the undetectable quarks and gluons.&nbsp;&nbsp;</p>
<p>A high-energy collider with the ability to collide electrons with the full range of nuclei at high rates and to have the electrons and nucleons polarized was identified as the essential tool to construct this bridge. High-energy electron scattering from the proton was how quarks were experimentally discovered at <a href="https://www6.slac.stanford.edu/about/slac-overview/about-our-name">SLAC</a> in the late 1960s (by MIT physics faculty Henry Kendall and Jerome Friedman and colleagues), and it is the accepted technique to directly probe the fundamental quark and gluon structure of matter.</p>
<p>Significant initial impetus for the EIC came from nuclear physicists at the university user-facilities at the University of Indiana and MIT as well as from physicists seeking to understand the origin of the proton’s spin, at laboratories and universities in the U.S. and Europe. Over the last three long-range planning exercises by U.S. nuclear physicists in 2002, 2007, and 2015, the case for the EIC has matured and strengthened. After the 2007 exercise, the two U.S. flagship nuclear facilities, namely the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Continuous Electron Beam Accelerator Facility at Jefferson Laboratory, took a leadership role in coordinating EIC activities across the broad U.S. QCD community. This led to the production in 2012 of a succinct summary of the science case, “Electron-Ion Collider: The Next QCD Frontier (Understanding the glue that binds us all).”&nbsp;</p>
<p>The 2015 planning exercise established the EIC as the highest priority for new facility construction in U.S. nuclear physics after present commitments are fulfilled.&nbsp;&nbsp;&nbsp; This led to the formation of a committee by the U.S. National Academy of Sciences (NAS) to assess the EIC science case. The NAS committee deliberated for about a year and the report has been publicly released this month.</p>
<p><strong>Q:</strong> Give us an idea of how powerful this new collider will be and what kind of new interactions it will produce. What kinds of phenomena will it help to explain?</p>
<p><strong>A:</strong> The EIC will be a powerful and unique new accelerator that will offer an unprecedented window into the fundamental structure of matter. The electron-ion collision rate at the EIC will be high, more than two orders of magnitude greater than was possible at the only previous electron-proton collider, namely HERA, which operated at the DESY laboratory in Hamburg, Germany, from 1992 to 2007.&nbsp; With the EIC, physicists will be able to image the virtual quarks and gluons that make up protons, neutrons, and nuclei, with unprecedented spatial resolution and shutter speed. A goal is to provide images of the fundamental structure of the microcosm that can be appreciated broadly by humanity: to answer questions such as, what does a proton look like? And what does a nucleus look like?</p>
<p>There are three central scientific issues that can be addressed by an electron-ion collider. The first goal is to understand in detail the mechanisms within QCD by which the mass of protons and neutrons, and thus the mass of all the visible matter in the universe, is generated. The problem is that while gluons have no mass, and quarks are nearly massless, the protons and neutrons that contain them are heavy, making up most of the visible mass of the universe. The total mass of a nucleon is some 100 times greater than the mass of the various quarks it contains.</p>
<p>The second issue is to understand the origin of the intrinsic angular momentum, or spin, of nucleons, a fundamental property that underlies many practical applications, including magnetic resonance imaging (MRI). How the angular momentum, both intrinsic as well as orbital, of the internal quarks and gluons gives rise to the known nucleon spin is not understood. And thirdly, the nature of gluons in matter — that is, their arrangements or states — and the details of how they hold matter together, is not well-known. Gluons in matter are a little like dark matter in the universe: unseen but playing a crucial role. An electron-ion collider would potentially reveal new states resulting from the close packing of many gluons within nucleons and nuclei. These issues are fundamental to our understanding of the matter in the universe.</p>
<p><strong>Q:</strong> What role will MIT have in this project going forward?</p>
<p><strong>A:</strong> At present, more than a dozen MIT physics department faculty lead research groups in the Laboratory for Nuclear Science that work directly on understanding the fundamental structure of matter as described by QCD. It is the largest university-based group in the U.S. working on QCD. Theoretical research is focused at the Center for Theoretical Physics, and experimentalists rely heavily on the Bates Research and Engineering Center for technical support.</p>
<p>MIT theorists are carrying out important calculations using the world’s most powerful computers to understand fundamental aspects of QCD. MIT experimental physicists are conducting experiments at existing facilities, such as BNL, CERN, and Jefferson Laboratory, to reach new insight and to develop new techniques that will be used at the EIC. Further, R&amp;D into new polarized sources, detectors, and innovative data-acquisition schemes by MIT scientists and engineers is in progress. It is anticipated that these efforts will ramp up as the realization of the EIC approaches.&nbsp;</p>
<p>It is anticipated that the U.S. Department of Energy Office of Science will initiate in the near future the official process for EIC by which the U.S. government approves, funds, and constructs new, large scientific facilities. Critical issues are the selection of the site for EIC and the participation of international users. An EIC user group has formed with the participation of more than 700 PhD scientists from over 160 laboratories and universities around the world. If the realization of EIC follows a schedule comparable to that of past large facilities, it should be doing science by about 2030. MIT has a long history of providing leadership in U.S. nuclear physics and will continue to play a significant role as we proceed along the path to EIC.&nbsp;</p>
In an Electron-Ion Collider, a beam of electrons (e-) would scatter off a beam of protons or atomic nuclei, generating virtual photons (λ) — particles of light that penetrate the proton or nucleus to tease out the structure of the quarks and gluons within.Image: Brookhaven National Laboratory3 Questions, Laboratory for Nuclear Science, Nuclear science and engineering, Physics, Research, School of Science, Department of Energy (DoE)School of Science appoints eight faculty members to named professorshipshttp://news.mit.edu/2018/school-science-appoints-eight-faculty-members-to-named-professorships-0723
Mon, 23 Jul 2018 10:00:00 -0400School of Sciencehttp://news.mit.edu/2018/school-science-appoints-eight-faculty-members-to-named-professorships-0723<p>The School of Science announced that eight of its faculty members have been appointed to named professorships. These positions afford the faculty members additional support to pursue their research and develop their careers.</p>
<p><a href="https://calolab.org/" target="_blank">Eliezer Calo</a>, assistant professor in the Department of Biology, has been named the Irwin W. and Helen Sizer Career Development Professor. He focuses on the coordination of RNA metabolism using a combination of genetic, biochemical, and functional genomic approaches. The core of Calo’s research program is to understand how ribosome biogenesis is controlled by specific RNA binding proteins, particularly RNA helicases of the “DEAD box” family, and how disregulation of ribosome biogenesis contributes to various diseases, including cancer. He proposes initially to characterize the functions of specific genes of interest, including the DDX21 RNA helicase and the TCOF1 factor involved in RNA Pol I transcription and rRNA processing, using biochemical, molecular and genome-wide approaches in mouse, Xenopus and Zebrafish models.</p>
<p><a href="http://flavell.mit.edu/" target="_blank">Steven Flavell</a>, assistant professor in the Department of Brain and Cognitive Sciences, has been named the Lister Brothers Career Development Professor. He uses <em>Caenorhabditis elegans</em> to examine how neuromodulators coordinate activity in neural circuits to generate locomotion behaviors linked to the feeding or satiety states of an animal. His long-term goal is to understand how neural circuits generate sustained behavioral states, and how physiological and environmental information is integrated into these circuits. Gaining a mechanistic understanding of how these circuits function will be essential to decipher the neural bases of sleep and mood disorders.</p>
<p><a href="http://jarilloherrero.mit.edu/" target="_blank">Pablo Jarillo-Herrero</a>, the Cecil and Ida Green Professor of Physics, explores quantum transport in novel condensed-matter systems such as graphene, transition metal dichalcogenides and topological insulators. In recent work, he has demonstrated the presence of a bandgap in graphene-based van der Waals heterostructures, novel quantum spin Hall and photothermoelectric effects in graphene, as well as light-emitting diodes, photodetectors and solar cells in the atomically thin tungsten diselenide system. He has also made advances in characterizing and manipulating the properties of other ultrathin materials such as ultrathin graphite and molybdenum disulphide, which lack graphene’s ultrarelativistic properties, but possess other unusual electronic properties.</p>
<p><a href="https://www.lamasonlab.org/" target="_blank">Becky Lamason</a>, assistant professor in the Department of Biology, has been named the Robert A. Swanson (1969) Career Development Professor of Life Sciences. She investigates how intracellular bacterial pathogens hijack host cell processes to promote infection. In particular, she studies how <em>Rickettsia parkeri</em> and <em>Listeria monocytogenes</em> move through tissues via a process called cell-to-cell spread. She utilizes cellular, molecular, genetic, biochemical, and biophysical approaches to elucidate the mechanisms of spread in order to reveal key aspects of pathogenesis and host cell biology.</p>
<p><a href="http://saxelab.mit.edu/" target="_blank">Rebecca Saxe</a>, the inaugural John W. Jarve (1978) Professor in Brain and Cognitive Sciences, is best known for her discovery of a brain region that is specialized for "theory of mind," people's ability to think about the thoughts, beliefs, plans, hopes and emotions of other people. Saxe continues to study this region and its role in social cognition, and is exploring the theory-of-mind system as a promising candidate for understanding the biological basis of autism. She also studies brain development in human babies, including her own.</p>
<p><a href="https://yilmaz-lab.mit.edu/" target="_blank">Omer Yilmaz</a>, assistant professor in the Department of Biology, has been named the Eisen and Chang Career Development Professor. He studies how the adult intestine is maintained by stem cells that require a cellular neighborhood, or niche, consisting in part of Paneth cells. Specifically, he investigates the molecular mechanisms of how intestinal stem cells and their Paneth cell niche respond to diverse diets to coordinate intestinal regeneration with organismal physiology and its impact on the formation and growth of intestinal cancers. By better understanding how intestinal stem cells adapt to diverse diets, he hopes to identify and develop new strategies that prevent and reduce the growth of cancers involving the intestinal tract that includes the small intestine, colon, and rectum.</p>
<p><a href="http://yufeizhao.com/" target="_blank">Yufei Zhao</a>, assistant professor in the Department of Mathematics, has been named the Class of 1956 Career Development Professor. He has made significant contributions in combinatorics with applications to computer science. Recently, Zhao and three undergraduates solved an open problem concerning the number of independent sets in an irregular graph, a conjecture first proposed in 2001. Understanding the number of independent sets — subsets of vertices where no two vertices are adjacent — is important to solving many other combinatorial problems. In other research accomplishments, Zhao co-authored a proof with Jacob Fox and David Conlon that contributed to a better understanding of the celebrated Green-Tao theorem that states prime numbers contain arbitrarily long arithmetic progressions. Their work improves our understanding of pseudorandom structures — non-random objects with random-like properties — and has other applications in mathematics and computer science.</p>
<p><a href="http://web.mit.edu/physics/people/faculty/zwierlein_martin.html" target="_blank">Martin Zwierlein</a>, the inaugural Thomas A. Frank (1977) Professor of Physics, studies ultracold gases of atoms and molecules. These gases host novel states of matter and serve as pristine model systems for other systems in nature, such as neutron stars or high-temperature superconductors. In contrast to bulk materials, in experiments with cold gases one can freely tune the interaction between atoms and make it as strong as quantum mechanics allows. This enabled the observation of a novel robust form of superfluidity: Scaled to the density of electrons in solids, superfluidity would in fact occur far above room temperature. Under a novel quantum gas microscope with single-atom resolution, the team recently studied charge and spin correlations and transport in a Fermi-Hubbard lattice gas. This system is believed to hold the key to high-temperature superconductivity in cuprate materials. Using ultracold molecules, Zwierlein’s group also demonstrated coherence times on the order of seconds, spurring hopes for the future use of such molecules in quantum information applications.</p>
Clockwise from top left: Eliezer Calo, Steven Flavell, Pablo Jarillo-Herrero, Becky Lamason, Rebecca Saxe, Omer Yilmaz, Yufei Zhao, and Martin Zwierlein.Faculty, Awards, honors and fellowships, Biology, Brain and cognitive sciences, Mathematics, Physics, School of ScienceNew study again proves Einstein right http://news.mit.edu/2018/new-study-high-energy-neutrinos-proves-einstein-right-0716
Most thorough test to date finds no Lorentz violation in high-energy neutrinos.Mon, 16 Jul 2018 11:00:00 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/new-study-high-energy-neutrinos-proves-einstein-right-0716<p>The universe should be a predictably symmetrical place, according to a cornerstone of Einstein’s theory of special relativity, known as Lorentz symmetry. This principle states that any scientist should observe the same laws of physics, in any direction, and regardless of one’s frame of reference, as long as that object is moving at a constant speed.</p>
<p>For instance, as a consequence of Lorentz symmetry, you should observe the same speed of light — 300 million meters per second — whether you are an astronaut traveling through space or a molecule moving through the bloodstream.</p>
<p>But for infinitesimally small objects that operate at incredibly high energies, and over vast, universe-spanning distances, the same rules of physics may not apply. At these extreme scales, there may exist a violation to Lorentz symmetry, or Lorentz violation, in which a mysterious, unknown field warps the behavior of these objects in a way that Einstein would not predict.</p>
<p>The hunt has been on to find evidence of Lorentz violation in various phenomena, from photons to gravity, with no definitive results. Physicists believe that if Lorentz violation exists, it might also be seen in neutrinos, the lightest known particles in the universe, which can travel over vast distances and are produced by cataclysmic high-energy astrophysical phenomena. Any confirmation that Lorentz violation exists would point to completely new physics that cannot be explained by Einstein’s theory.</p>
<p>Now MIT scientists and their colleagues on the IceCube Experiment have led the most thorough search yet of Lorentz violation in neutrinos. They analyzed two years of data collected by the IceCube Neutrino Observatory, a massive neutrino detector buried in the Antarctic ice. The team searched for variations in the normal oscillation of neutrinos that could be caused by a Lorentz-violating field. According to their analysis, no such abnormalities were observed in the data, which comprises the highest-energy atmospheric neutrinos that any experiment has collected.</p>
<p>The team’s results, published today in <em>Nature Physics</em>, rule out the possibility of Lorentz violation in neutrinos within the high energy range that the researchers analyzed. The results establish the most stringent limits to date on the existence of Lorentz violation in neutrinos. They also provide evidence that neutrinos behave just as Einstein’s theory predicts.</p>
<p>“People love tests of Einstein’s theory,” says Janet Conrad, professor of physics at MIT and a lead author on the paper. “I can’t tell if people are cheering for him to be right or wrong, but he wins in this one, and that’s kind of great. To be able to come up with as versatile a theory as he has done is an incredible thing.”</p>
<p>Conrad’s co-authors at MIT, who also led the search for Lorentz violation, are postdoc Carlos Argüelles and graduate student Gabriel Collin, who collaborated closely with Teppei Katori, a former postdoc in Conrad’s group who is now a lecturer in particle physics at Queen Mary University of London. Their co-authors on the paper include the entire IceCube Collaboration, comprising more than 300 researchers from 49 institutions in 12 countries.</p>
<p><strong>Flavor change</strong></p>
<p>Neutrinos exist in three main varieties, or as particle physicists like to call them, “flavors”: electron, muon, and tau. As a neutrino travels through space, its flavor can oscillate, or morph into any other flavor. The way neutrinos oscillate typically depends on a neutrino’s mass or the distance that it has traveled. But if a Lorentz-violating field exists somewhere in the universe, it could interact with neutrinos passing through that field, and affect their oscillations.</p>
<p>To test whether Lorentz violation can be found in neutrinos, the researchers looked to data gathered by the IceCube Observatory. IceCube is a 1-gigaton particle-detector designed to observe high-energy neutrinos produced from the most violent astrophysical sources in the universe. The detector is composed of 5,160 digital optical modules, or light sensors, each of which are attached to vertical strings that are frozen into 86 boreholes arrayed over a cubic kilometer of Antarctic ice.</p>
<p>Neutrinos streaming through space and the Earth can interact with the ice that comprises the detector or the bedrock below it. This interaction produces muons — charged particles that are heavier than electrons. Muons emit light as they go through the ice, producing long tracks that can go through the entire detector. Based on the recorded light, scientists can track the trajectory and estimate the energy of a muon, which they can use to back-calculate the energy — and expected oscillation — of the original neutrino.</p>
<p>The team, led by Argüelles and Katori, decided to look for Lorentz violation in the highest-energy neutrinos that are produced in the Earth’s atmosphere.</p>
<p>“Neutrino oscillations are a natural interferometer,” explains Katori. “Neutrino oscillations observed with IceCube act as the biggest interferometer in the world to look for the tiniest effects such as a space-time deficit.”</p>
<p>The team looked through two years of data gathered by IceCube, which comprised more than 35,000 interactions between a muon neutrino and the detector. If a Lorentz-violating field exists, the researchers theorized that it should produce an abnormal pattern of oscillations from neutrinos arriving at the detector from a particular direction, which should become more relevant as the energy increases. Such an abnormal oscillation pattern should correspond to a similarly abnormal energy spectrum for the muons.</p>
<p>The researchers calculated the deviation in the energy spectrum that they would expect to see if Lorentz violation existed, and compared this spectrum to the actual energy spectrum IceCube observed, for the highest-energy neutrinos from the atmosphere.</p>
<p>“We are looking for a deficit of muon neutrinos along the direction that traverses large fractions of the Earth,” Argüelles says. “This Lorentz violation-induced disappearance should increase with increasing energy.”</p>
<p>If Lorentz violation exists, physicists believe it should have a more obvious effect on objects at extremely high energies. The atmospheric neutrino dataset analyzed by the team is the highest-energy neutrino data collected by any experiment.</p>
<p>“We were looking to see if a Lorentz violation caused a deviation, and we didn’t see it,” Conrad says. “This closes the book on the possibility of Lorentz violation for a range of high-energy neutrinos, for a very long time.”</p>
<p><strong>A violating limit</strong></p>
<p>“This is a difficult analysis and takes into account effects that had not been considered before,” says Andre Luiz De Gouvea, a physics professor at Northwestern University, who was not involved in the research. “It is, as of right now, the most powerful result of its kind.”</p>
<p>The team’s results set the most stringent limit yet on how strongly neutrinos may be affected by a Lorentz-violating field. The researchers calculated, based on IceCube data, that a violating field with an associated energy greater than 10<sup>-36</sup> GeV<sup>-2</sup> should not affect a neutrino’s oscillations. That’s .01 with 35 more zeros preceding the 1, of one-billionth an electronvolt squared— an extremely small force that is far weaker than neutrinos’ normally weak interactions with the rest of matter, which is at the level of 10<sup>-5</sup> GeV<sup>-2</sup>.</p>
<p>“We were able to set limits on this hypothetical field that are much, much better than any that have been produced before,” Conrad says. “This was an attempt to go out and look at new territory we hadn’t looked at before and see if there are any problems in that space, and there aren’t. But that doesn’t stop us from looking further.”</p>
<p>To that point, the group plans to look for Lorentz violation in even higher-energy neutrinos that are produced from astrophysical sources. IceCube does record astrophysical neutrinos, along with atmospheric ones, but scientists don’t have a complete understanding of their behavior, such as their normal oscillations. Once they can better model these interactions, Conrad says the team will have a better chance of looking for patterns that deviate from the norm.</p>
<p>“Every paper that comes out of particle physics assumes that Einstein is right, and all the rest of our work builds on that,” Conrad says. “And to a very good approximation, he’s correct. It is a fundamental fabric of our theory. So trying to understand whether there are any deviations to it is a really important thing to do.”</p>
<p>This research was supported, in part, by National Science Foundation.</p>
The IceCube Lab at the South PoleImage: Martin Wolf, IceCube/NSFAstrophysics, Laboratory for Nuclear Science, Physics, Neutrinos, Research, School of Science, National Science Foundation (NSF)3Q: Janet Conrad on the first detection of a neutrino’s cosmic sourcehttp://news.mit.edu/2018/3q-janet-conrad-first-detection-neutrino-cosmic-source-0713
The “ghostly particle” is confirmed to have originated from a blazar, nearly 4 billion light years from Earth.Fri, 13 Jul 2018 11:30:00 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/3q-janet-conrad-first-detection-neutrino-cosmic-source-0713<p><em>For the first time, scientists from around the world have detected a source of high-energy cosmic neutrinos — subatomic particles, produced in the aftermath of explosive astrophysical phenoma, that streak across the universe by the billions, leaving very little trace of their presence.</em></p>
<p><em>Neutrinos, Italian for “little neutral ones,” are often described as “ghost particles,” for their extremely weak interactions with ordinary matter. Indeed, billions of neutrinos stream through our fingernails every second, without ruffling so much as a molecule of matter.&nbsp; And yet, on Sept. 22, 2017, the IceCube Neutrino Observatory, based at the Amundsen-Scott South Pole Station, detected a neutrino in signals picked up by its detectors buried deep in the Antarctic ice. Researchers there quickly sent out alerts to ground- and space-based telescopes in hopes of finding the neutrino’s cosmic source. </em></p>
<p><em>An answer was soon confirmed: The neutrino originated from a blazar — an active galaxy with a black hole at its center — about 3.7 billion light years away. The blazar, known to astronomers as </em><em>TXS 0506+056</em><em>, can be seen in the night sky just off the shoulder of the Orion constellation. </em></p>
<p><em>The findings, published today in two papers in </em>Science<em>, help to resolve a longstanding debate over the kinds of processes that send neutrinos speeding through the universe. Based on the results, researchers now know that blazars can produce neutrinos energetic enough to reach Earth from billions of light years across the universe. </em></p>
<p><em>Because blazars produce neutrinos, they also likely generate cosmic rays. The sources of cosmic rays, which continually rain down on Earth, have been a mystery. Unlike neutrinos, which interact weakly, and therefore stream blithely and directly through space, cosmic rays are charged particles whose paths can easily veer in response to magnetic fields. Cosmic ray sources, therefore, can be difficult to track. The new findings provide evidence that blazars are not only sources but also powerful accelerators of both neutrinos and cosmic rays. </em></p>
<p><em>Janet Conrad, professor of physics at MIT, is a member of the IceCube Collaboration, which encompasses more than 300 scientists around the world, and is a co-author of both papers. Conrad spoke with </em>MIT News<em> about the race to trace the neutrino to its distant, powerful source. &nbsp;&nbsp;</em></p>
<p><strong>Q:</strong> &nbsp;Give us an idea of what it took to find these neutrinos and their very specific source. How did IceCube do this?</p>
<p><strong>A:</strong> This discovery could only have happened with a monumental detector like&nbsp;IceCube.&nbsp;It is literally gigatons of ice instrumented with detectors&nbsp;that can observe light. These detectors are located about a mile below&nbsp;the ice.&nbsp;The prototype was constructed in the 1990s. IceCube began in&nbsp;2005 and took five years to construct. It took us about five years to learn&nbsp;how to analyze the data quickly enough to be able to send alerts to&nbsp;other telescopes that look for electromagnetic signals.&nbsp;We can now do&nbsp;this in about one minute.</p>
<p>The neutrino event that happened on Sept. 22, 2017, lit up a straight line of light collectors that is half a mile in length.&nbsp;Because it formed such a straight line, we could point backward into the sky to know its direction of origin.&nbsp;We have had high-energy, very linear events like this.&nbsp;Each time they arrive, we send out a notice to the community called an “astronomer's telegram” saying “Look this way!”&nbsp;And this time, it worked!&nbsp;They saw something!&nbsp;</p>
<p>The Fermi gamma-ray telescope, based in space, followed up within about a day looking in the direction the track pointed. They sent an astronomer’s telegram that followed ours, saying that the neutrino event position coincided with a blazar. Other telescopes on Earth, including MAGIC, then responded. So while it took only a minute to see and announce our event, this was built on years of work by us and by the telescopes that joined us in this discovery.</p>
<p><strong>Q:</strong> Tell us a bit about what kind of journey these neutrinos must have taken from their source and finally to Earth?</p>
<p><strong>A:</strong> A blazar is an active galaxy that contains a black hole.&nbsp;The black&nbsp;hole is spinning quickly, powering jets of particles and photons that&nbsp;spurt out the bottom and top.&nbsp;This particular blazar is 3.7 billion&nbsp;light-years away from us. A light-year is about 6 trillion miles. So this source is very far away! Between us and the blazar, there are strong magnetic fields that will bend away charged particles,&nbsp;and there is dust that will absorb photons. But neutrinos interact&nbsp;only weakly. They are not deflected by a magnetic field. They are&nbsp;very unlikely to interact in the dust, and so the neutrinos produced in&nbsp;the jet come directly to us.&nbsp;</p>
<p>In fact, even in the Earth, neutrinos&nbsp;will interact rarely, so this neutrino probably came with companions&nbsp;that we did not detect.&nbsp;This blazar has flared before! So we looked&nbsp;in our data, and we found that in 2014 there were multiple events coming from the direction of this blazar. Since we have seen neutrinos in&nbsp;coincidence with this blazar more than once, this result is especially&nbsp;compelling.</p>
<p><strong>Q:</strong> What to you makes this particular discovery so exciting?</p>
<p><strong>A:</strong> Neutrinos do very interesting things along their path.&nbsp;Neutrinos are&nbsp;produced in one of three types or “flavors,” and then they will change&nbsp;flavors as they travel due to a quantum mechanical effect called&nbsp;neutrino oscillations.&nbsp;So, though we observe a neutrino of the “muon”&nbsp;type, we don't know what flavor it began with.&nbsp;Also, we do not know&nbsp;if neutrinos have extra interactions or properties beyond those we&nbsp;describe in our “Standard Model” — the theory of particle physics. A&nbsp;neutrino that has traveled for such a long distance and at this high&nbsp;energy provides a very interesting test of our model.&nbsp;We had seen&nbsp;astrophysical neutrinos before but did not know where they came from.&nbsp;This extra information about the position of its origin makes the event&nbsp;very exciting to particle physicists like those of us in the MIT neutrino group, as well as to astrophysicists.</p>
<p><em>Conrad’s group members who are also members of the IceCube Collaboration include graduate students Marjon Moulai, Spencer Axani, and Gabriel Collin, and postdoc Carlos Arguelles. </em></p>
In this illustration, a neutrino has interacted with a molecule of ice, producing a secondary particle—a muon—that moves at relativistic speed in the ice, leaving a trace of blue light behind it.Image: Nicolle R. Fuller/NSF/IceCube3 Questions, Neutrinos, Astronomy, Astrophysics, Black holes, Physics, Research, School of Science, space, Space, astronomy and planetary science, Laboratory for Nuclear ScienceCould gravitational waves reveal how fast our universe is expanding?http://news.mit.edu/2018/gravitational-waves-reveal-fast-universe-expanding-0712
Signals from rare black hole-neutron star pairs could pinpoint rate at which universe is growing, researchers say.Thu, 12 Jul 2018 00:00:00 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/gravitational-waves-reveal-fast-universe-expanding-0712<p>Since it first exploded into existence 13.8 billion years ago, the universe has been expanding, dragging along with it hundreds of billions of galaxies and stars, much like raisins in a rapidly rising dough.</p>
<p>Astronomers have pointed telescopes to certain stars and other cosmic sources to measure their distance from Earth and how fast they are moving away from us — two parameters that are essential to estimating the Hubble constant, a unit of measurement that describes the rate at which the universe is expanding.</p>
<p>But to date, the most precise efforts have landed on very different values of the Hubble constant, offering no definitive resolution to exactly how fast the universe is growing. This information, scientists believe, could shed light on the universe’s origins, as well as its fate, and whether the cosmos will expand indefinitely or ultimately collapse.</p>
<p>Now scientists from MIT and Harvard University have proposed a more accurate and independent way to measure the Hubble constant, using gravitational waves emitted by a relatively rare system: a black hole-neutron star binary, a hugely energetic pairing of a spiraling black hole and a neutron star. As these objects circle in toward each other, they should produce space-shaking gravitational waves and a flash of light when they ultimately collide.</p>
<p>In a paper published today in <em>Physical Review Letters</em>, the researchers report that the flash of light would give scientists an estimate of the system’s velocity, or how fast it is moving away from the Earth. The emitted gravitational waves, if detected on Earth, should provide an independent and precise measurement of the system’s distance. Even though black hole-neutron star binaries are incredibly rare, the researchers calculate that detecting even a few should yield the most accurate value yet for the Hubble constant and the rate of the expanding universe.</p>
<p>“Black hole-neutron star binaries are very complicated systems, which we know very little about,” says Salvatore Vitale, assistant professor of physics at MIT and lead author of the paper. “If we detect one, the prize is that they can potentially give a dramatic contribution to our understanding of the universe.”</p>
<p>Vitale’s co-author is Hsin-Yu Chen of Harvard.</p>
<p><strong>Competing constants</strong></p>
<p>Two independent measurements&nbsp; of the Hubble constant were made recently, one using NASA's Hubble Space Telescope and another using the European Space Agency's Planck satellite. The Hubble Space Telescope’s measurement is based on observations of a type of star known as a Cepheid variable, as well as on observations of supernovae. Both of these objects are considered “standard candles,” for their predictable pattern of brightness, which scientists can use to estimate the star’s distance and velocity.</p>
<p>The other type of estimate is based on observations of the fluctuations in the cosmic microwave background — the electromagnetic radiation that was left over in the immediate aftermath of the Big Bang, when the universe was still in its infancy. While the observations by both probes are extremely precise, their estimates of the Hubble constant disagree significantly.</p>
<p>“That’s where LIGO comes into the game,” Vitale says.</p>
<p>LIGO, or the Laser Interferometry Gravitational-Wave Observatory, <a href="http://news.mit.edu/2016/ligo-first-detection-gravitational-waves-0211">detects gravitational waves</a> — ripples in the Jell-O of space-time, produced by cataclysmic astrophysical phenomena.</p>
<p>“Gravitational waves provide a very direct and easy way of measuring the distances of their sources,” Vitale says. “What we detect with LIGO is a direct imprint of the distance to the source, without any extra analysis.”</p>
<p>In 2017, scientists got their first chance at estimating the Hubble constant from a gravitational-wave source, when LIGO and its Italian counterpart Virgo detected a pair of <a href="http://news.mit.edu/2017/ligo-virgo-first-detection-gravitational-waves-colliding-neutron-stars-1016">colliding neutron stars</a> for the first time. The collision released a huge amount of gravitational waves, which researchers measured to determine the distance of the system from Earth. The merger also released a flash of light, which astronomers focused on with ground and space telescopes to determine the system’s velocity.</p>
<p>With both measurements, scientists calculated a new value for the Hubble constant. However, the estimate came with a relatively large uncertainty of 14 percent, much more uncertain than the values calculated using the Hubble Space Telescope and the Planck satellite.</p>
<p>Vitale says much of the uncertainty stems from the fact that it can be challenging to interpret a neutron star binary’s distance from Earth using the gravitational waves that this particular system gives off.&nbsp; &nbsp;</p>
<p>“We measure distance by looking at how ‘loud’ the gravitational wave is, meaning how clear it is in our data,” Vitale says. “If it’s very clear, you can see how loud it is, and that gives the distance. But that’s only partially true for neutron star binaries.”</p>
<p>That’s because these systems, which create a whirling disc of energy as two neutron stars spiral in toward each other, emit gravitational waves in an uneven fashion. The majority of gravitational waves shoot straight out from the center of the disc, while a much smaller fraction escapes out the edges. If scientists detect a “loud” gravitational wave signal, it could indicate one of two scenarios: the detected waves stemmed from the edge of a system that is very close to Earth, or the waves emanated from the center of a much further system.</p>
<p>“With neutron star binaries, it’s very hard to distinguish between these two situations,” Vitale says.</p>
<p><strong>A new wave</strong></p>
<p>In 2014, before LIGO made the first detection of gravitational waves, Vitale and his colleagues observed that a binary system composed of a black hole and a neutron star could give a more accurate distance measurement, compared with neutron star binaries. The team was investigating how accurately one could measure a black hole’s spin, given that the objects are known to spin on their axes, similarly to Earth but much more quickly.</p>
<p>The researchers simulated a variety of systems with black holes, including black hole-neutron star binaries and neutron star binaries. As a byproduct of this effort, the team noticed that they were able to more accurately determine the distance of black hole-neutron star binaries, compared to neutron star binaries. Vitale says this is due to the spin of the black hole around the neutron star, which can help scientists better pinpoint from where in the system the gravitational waves are emanating.</p>
<p>“Because of this better distance measurement, I thought that black hole-neutron star binaries could be a competitive probe for measuring the Hubble constant,” Vitale says. “Since then, a lot has happened with LIGO and the discovery of gravitational waves, and all this was put on the back burner.”</p>
<p>Vitale recently circled back to his original observation, and in this new paper, he set out to answer a theoretical question:</p>
<p>“Is the fact that every black hole-neutron star binary will give me a better distance going to compensate for the fact that potentially, there are far fewer of them in the universe than neutron star binaries?” Vitale says.</p>
<p>To answer this question, the team ran simulations to predict the occurrence of both types of binary systems in the universe, as well as the accuracy of their distance measurements. From their calculations, they concluded that, even if neutron binary systems outnumbered black hole-neutron star systems by 50-1, the latter would yield a Hubble constant similar in accuracy to the former.</p>
<p>More optimistically, if black hole-neutron star binaries were slightly more common, but still rarer than neutron star binaries, the former would produce a Hubble constant that is four times as accurate.</p>
<p>“So far, people have focused on binary neutron stars as a way of measuring the Hubble constant with gravitational waves,” Vitale says. “We’ve shown there is another type of gravitational wave source which so far has not been exploited as much: black holes and neutron stars spiraling together,” Vitale says. “LIGO will start taking data again in January 2019, and it will be much more sensitive, meaning we’ll be able to see objects farther away. So LIGO should see at least one black hole-neutron star binary, and as many as 25, which will help resolve the existing tension in the measurement of the Hubble constant, hopefully in the next few years.”</p>
<p>This research was supported, in part, by the National Science Foundation and the LIGO Laboratory.</p>
Numerical simulation of the last instances of a neutron star and black hole merger, as the neutron star is destroyed by the tidal pull of the black hole (at the center of the disk).Image: A. Tonita, L. Rezzolla, F. PannaraleAstronomy, Astrophysics, Black holes, Kavli Institute, LIGO, Physics, Research, School of Science, space, Space, astronomy and planetary science, National Science Foundation (NSF)Project to elucidate the structure of atomic nuclei at the femtoscalehttp://news.mit.edu/2018/project-to-elucidate-structure-of-atomic-nuclei-at-femtoscale-0706
Laboratory for Nuclear Science project selected to explore machine learning for lattice quantum chromodynamics.Fri, 06 Jul 2018 14:00:00 -0400Scott Morley | Laboratory for Nuclear Sciencehttp://news.mit.edu/2018/project-to-elucidate-structure-of-atomic-nuclei-at-femtoscale-0706<p>The Argonne Leadership Computing Facility (ALCF), a U.S. Department of Energy (DOE) Office of Science User Facility, has selected 10 data science and machine learning projects for its Aurora Early Science Program (ESP). Set to be the nation’s first exascale system upon its expected 2021 arrival, Aurora will be capable of performing a quintillion calculations per second, making it 10 times more powerful than the fastest computer that currently exists.</p>
<p>The Aurora ESP, which commenced with 10 simulation-based projects in 2017, is designed to prepare key applications, libraries, and infrastructure for the architecture and scale of the exascale supercomputer. Researchers in the Laboratory for Nuclear Science’s Center for Theoretical Physics have been awarded funding for one of the projects under the ESP. Associate professor of physics William Detmold, assistant professor of physics Phiala Shanahan, and principal research scientist Andrew Pochinsky will use new techniques developed by the group, coupling novel machine learning approaches and state-of-the-art nuclear physics tools, to study the structure of nuclei.</p>
<p>Shanahan, who began as an assistant professor at MIT this month, says that the support and early access to frontier computing that the award provides will allow the group to study the possible interactions of dark matter particles with nuclei from our fundamental understanding of particle physics for the first time, providing critical input for experimental searches aiming to unravel the mysteries of dark matter while simultaneously giving insight into fundamental particle physics.</p>
<p>“Machine learning coupled with the exascale computational power of Aurora will enable&nbsp;spectacular advances in many areas of science,”&nbsp;Detmold adds. “Combining machine learning to lattice quantum chromodynamics&nbsp;calculations of the strong interactions between the fundamental particles that make up protons and nuclei, our project&nbsp;will enable a new level of understanding of the femtoscale world.”</p>
The image is an artist’s visualization of a nucleus as studied in numerical simulations, created using DeepArt neural network visualization software.Image courtesy of the Laboratory for Nuclear Science.Research, Laboratory for Nuclear Science, Physics, Center for Theoretical Physics, Department of Energy (DoE), School of Science, Machine learning, Supercomputing, Computer science and technology, Data, FundingInstitute Archives spotlights pioneering women at MIThttp://news.mit.edu/2018/institute-archives-spotlights-pioneering-mit-women-0706
Initiative is building collections highlighting the contributions of female faculty.
Fri, 06 Jul 2018 11:50:01 -0400Brigham Fay | MIT Librarieshttp://news.mit.edu/2018/institute-archives-spotlights-pioneering-mit-women-0706<p>A new MIT Libraries initiative aims to highlight MIT’s women faculty by acquiring, preserving, and making accessible their personal archives. The Institute Archives and Special Collections (IASC) launched the project last year with the generous support of Barbara Ostrom ’78 and Shirley Sontheimer.</p>
<p>The first year of the project has focused on reaching out to faculty who are ending the active phase of their careers. Four faculty members added their personal collections, comprising 234 boxes and 50 gigabytes of material. They are:</p>
<ul>
<li><a href="https://biology.mit.edu/profile/nancy-hopkins/" target="_blank">Nancy Hopkins</a>, the Amgen Inc. Professor of Biology Emerita, known for making zebrafish a widely used research tool and for bringing about an investigation that resulted in the landmark 1999 report on the status of women at MIT;<br />
&nbsp;</li>
<li><a href="https://bcs.mit.edu/users/mpottermitedu" target="_blank">Mary Potter</a>, professor emerita in the Department of Brain and Cognitive Sciences, former chair of the MIT faculty, and member of the Committee of Women Faculty in the School of Science, whose research and teaching focused on experimental methods to study human cognition;<br />
&nbsp;</li>
<li><a href="http://mitsloan.mit.edu/faculty-and-research/faculty-directory/detail/?id=41344" target="_blank">Mary Rowe</a>, adjunct professor at the MIT Sloan School of Management, special assistant to the president, and ombudsperson, a conflict resolution specialist whose work led to MIT having one of the nation’s first anti-harassment policies; and<br />
&nbsp;</li>
<li><a href="http://aeroastro.mit.edu/faculty-research/faculty-list/sheila-widnall" target="_blank">Sheila Widnall</a> ’60, SM ’61, ScD ’64, Institute Professor and professor of aeronautics and astronautics, the first woman to serve as secretary of the Air Force, and the first woman to lead an entire branch of the U.S. military.</li>
</ul>
<p>A donation of the papers of <a href="http://news.mit.edu/2017/institute-professor-emerita-mildred-dresselhaus-dies-86-0221" target="_self">Mildred Dresselhaus</a>, late Institute Professor emerita of electrical engineering and computer science and physics, is also forthcoming. Dresselhaus, whose work paved the way for much of today’s carbon-based nanotechnology, was also known for promoting opportunities for women in science and engineering. Discussions with additional faculty are also underway.</p>
<p>“We are honored to be stewards of these personal archives that have been given to MIT,” says Liz Andrews, project archivist. “We’re committed to preserving and making accessible these unique materials so they can be shared with the world into the future.”</p>
<p>Acquisitions of MIT administrative records provide additional context to the personal archives and a broader view on issues of gender equity and the challenges faced by women in academia. In the next phase of the project, archivists will continue to manage donations, prepare collections for use, and enlarge this core group by reaching out to female faculty who were tenured in the 1960s, '70s, and '80s.</p>
<p>Ultimately, the collections will provide not only rich resources for researchers, journalists, teachers, and students, but also, as Sontheimer says, inspiration for generations of women to come. “I’m hoping the project will encourage more women to become engaged in science, technology, and engineering,” she says.</p>
Nancy Hopkins (center) stands with Salvador Luria (left) and David Baltimore at the MIT Cancer Center in the 1980s.Photo courtesy of the MIT Museum.Libraries, Women in STEM, Faculty, History of MIT, History, Women, Biology, Brain and cognitive sciences, Physics, Electrical Engineering & Computer Science (eecs), School of Science, School of Engineering, Sloan School of Management, Aeronautical and astronautical engineering, Diversity and inclusionAt 99, Lew Aronin ’40 volunteers for MIT AgeLab http://news.mit.edu/2018/99-alumnus-lew-aronin-volunteers-age-lab-0628
Physics alumnus who saw the Hindenburg fly over campus now collaborates with researchers to explore the impacts of longevity.Thu, 28 Jun 2018 00:00:00 -0400Nancye Mims | MIT Alumni Associationhttp://news.mit.edu/2018/99-alumnus-lew-aronin-volunteers-age-lab-0628<p>As a volunteer for MIT’s AgeLab, 99-year-old Lew Aronin ’40 is doing what he loves most<em> — </em>seeking scientific knowledge for the benefit of humankind. A physics alum­nus who attends MIT events and donates annually, Aronin is a member of <a href="http://agelab.mit.edu/85-lifestyle-leaders-panel">85+ Lifestyle Leaders</a>, a group of people 85 and older, including many alumni and spouses, who delve into topics such as age-friendly design, caregiv­ing, and use of technology.</p>
<p>Aronin’s career began during World War II: The Waltham Watch Company hired him to reproduce the verneuil process for making synthetic sapphires, which are an important compo­nent of watch bearings. “If the company’s supply from Switzerland was cut off, there was a great fear that the only source of preci­sion bearings would be lost,” says Aronin. “I successfully did this in less than a year.”</p>
<p>When the company folded, Aronin joined the staff of the MIT Metallurgical Proj­ect, where he also consulted on the development of the atomic bomb. His research focused on nuclear reactors, and he published an article on radiation damage in the <em>Journal of Applied Physics </em>in 1954. After his department spun off to become a com­pany called Nuclear Metals, he worked as a department manager, and he also con­tributed two chapters to a textbook called <em>Nuclear Reactor Fuel Elements Metal­lurgy and Fabrication</em>.</p>
<p>Aronin first encountered the Institute when his sci­ence teacher in Norwood, Massachusetts, took his best students to attend lec­tures by notables like Harold “Doc” Edgerton and Robert Van de Graaff. The lectures and the campus won him over. Unable to afford a dor­mitory, Aronin commuted and had a part-time job on campus. “I worked hard and got into MIT with the odds against me,” he says, “and it has served me well.”</p>
<p>One first-year experi­ence left a big impression. On May 6, 1937, while work­ing on a problem set in Build­ing 2, he noticed a sudden darkness. When he looked outside, he saw the <em>Hinden­burg </em>overhead, with swasti­kas on its tail. Three hours later, it crashed in Manches­ter Township, New Jersey.</p>
<p>He and his late wife, Eleanor, a musician, were married for 59 years. They raised their children in Lex­ington, Massachusetts, where she became a sought-after piano teacher; he was an active volunteer for the Lions Club and Masons.</p>
<p>Aronin, who retired in 1990, finished his career at the Army Research Labora­tory in Watertown, where he was an expert in beryllium, a relatively rare chemical ele­ment used in cell phones, missiles, and aircraft.</p>
<p><em>A version of this article originally appeared on the </em><a href="https://slice.mit.edu/" target="_blank">Slice of MIT</a><em> blog</em></p>
Lew Aronin '40 is a frequent and enthusiastic participant in Tech Reunions.Photo courtesy of the MIT Alumni AssociationAlumni/ae, Community, Aging, Volunteering, outreach, public service, Physics, History of MITNearly 80 exoplanet candidates identified in record timehttp://news.mit.edu/2018/nearly-80-exoplanet-candidates-identified-record-time-0621
Search considered successful “dress rehearsal” for exoplanet hunter TESS.Wed, 20 Jun 2018 23:59:59 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/nearly-80-exoplanet-candidates-identified-record-time-0621<p>Scientists at MIT and elsewhere have analyzed data from K2, the follow-up mission to NASA’s Kepler Space Telescope, and have discovered a trove of possible exoplanets amid some 50,000 stars.</p>
<p>In a paper that appears online today in <em>The Astronomical Journal</em>, the scientists report the discovery of nearly 80 new planetary candidates, including a particular standout: a likely planet that orbits the star HD 73344, which would be the brightest planet host ever discovered by the K2 mission.</p>
<p>The planet appears to orbit HD 73344 every 15 days, and based on the amount of light that it blocks each time it passes in front of its star, scientists estimate that the planet is about 2.5 times the size of the Earth and 10 times as massive. It is also likely incredibly hot, with a temperature somewhere in the range of 1,200 to 1,300 degrees Celsius, or around 2,000 degrees Fahrenheit — about the the temperature of lava from an erupting volcano.</p>
<p>The planet lies at a relatively close distance of 35 parsecs, or about 114 light years from Earth. Given its proximity and the fact that it orbits a very bright star, scientists believe the planet is an ideal candidate for follow-up studies to determine its atmospheric composition and other characteristics.</p>
<p>“We think it would probably be more like a smaller, hotter version of Uranus or Neptune,” says Ian Crossfield, an assistant professor of physics at MIT who co-led the study with graduate student Liang Yu.</p>
<p>The new analysis is also noteworthy for the speed with which it was performed. The researchers were able to use existing tools developed at MIT to rapidly search through graphs of light intensity called “lightcurves” from each of the 50,000 stars that K2 monitored in its two recent observing campaigns. They quickly identified the planetary candidates and released the information to the astronomy community just weeks after the K2 mission made the spacecraft’s raw data available. A typical analysis of this kind takes between several months and a year.</p>
<p>Crossfield says such a fast planet-search enables astronomers to follow up with ground-based telescopes much sooner than they otherwise would, giving them a chance to catch a glimpse of planetary candidates before the Earth passes by that particular patch of sky on its way around the sun.</p>
<p>Such speed will also be a necessity when scientists start receiving data from NASA’s Transiting Exoplanet Survey Satellite, TESS, which is designed to monitor nearby stars in 30-day swaths and will ultimately cover nearly the entire sky.</p>
<p>“When the TESS data come down, there’ll be a few months before all of the stars that TESS looked at for that month ‘set’ for the year,” Crossfield says. “If we get candidates out quickly to the community, everyone can start immediately observing systems discovered by TESS, and doing a lot of great planetary science. So this [analysis] was really a dress rehearsal for TESS.”</p>
<p><strong>Speed dips</strong></p>
<p>The team analyzed data from K2’s 16th and 17th observing campaigns, known as C16 and C17. During each campaign, K2 observes one patch of the sky for 80 days. The telescope is on an orbit that trails the Earth as it travels around the sun. For most other campaigns, K2 has been in a “rear-facing” orientation, in which the telescope observes those stars that are essentially in its rear-view mirror.</p>
<p><img alt="" src="/sites/mit.edu.newsoffice/files/fast-planet.gif" style="width: 595px; height: 335px;" /></p>
<p>Since the telescope travels behind the Earth, those stars that it observes are typically not observable by scientists until the planet circles back around the sun to that particular patch of sky, nearly a year later. Thus, for rear-facing campaigns, Crossfield says there has been little motivation to analyze K2 data quickly.</p>
<p>The C16 and C17 campaigns, on the other hand, were forward-facing; K2 observed those stars that were in front of the telescope and within Earth’s field of view, at least for the next several months. Crossfield, Yu, and their colleagues took this as an opportunity to speed up the usual analysis of K2 data, to give astronomers a chance to quickly observe planetary candidates before the Earth passed them by.</p>
<p>During C16, K2 observed 20,647 stars over 80 days, between Dec. 7, 2017, and Feb. 25, 2018. On Feb. 28, the mission released the data, in the form of pixel-level images, to the astronomy community. Yu and Crossfield immediately began to sift through the data, using algorithms developed at MIT to winnow down the field from 20,000-some stars to 1,000 stars of interest.</p>
<p>The team then worked around the clock, looking through these 1,000 stars by eye for signs of transits, or periodic dips in starlight that could signal a passing planet. In the end, they discovered 30 “highest-quality” planet candidates, whose periodic signatures are especially likely to be caused by transiting planets.</p>
<p>“Our experience with four years of K2 data leads us to believe that most of these are indeed real planets, ready to be confirmed or statistically validated,” the researchers write in their paper.</p>
<p>They also identified a similar number of planet candidates in the recent C17 analysis. In addition to these planetary candidates, the group also picked out hundreds of periodic signals that could be signatures of astrophysical phenomena, such as pulsating or rotating stars, and at least one supernova in another galaxy.</p>
<p><strong>Stars in spades</strong></p>
<p>While the nature of a star doesn’t typically change over the course of a year, Crossfield says the sooner researchers can follow up on a possible planetary transit, the better chance there is of confirming that a planet actually exists.</p>
<p>“You want to observe [candidates] again relatively soon so you don’t lose the transit altogether,” Crossfield says. “You might be able to say, ‘I know there’s a planet around that star, but I’m no longer at all certain when the transits will happen.’ That’s another motivation for following these things up more quickly.”</p>
<p>Since the team released its results, astronomers have validated four of the candidates as definite exoplanets. They have been observing other candidates that the study identified, including the possible planet orbiting HD 73344. Crossfield says the brightness of this star, combined with the speed with which its planetary candidate was identified, can help astronomers quickly zero in on even more specific features of this system.</p>
<p>“We found one of the most exciting planets that K2 has found in its entire mission, and we did it more rapidly than any effort has done before,” Crossfield says. “This is showing the path forward for how the TESS mission is going to do the same thing in spades, all over the entire sky, for the next several years.”</p>
<p>This research was supported, in part, by NASA and the National Science Foundation.</p>
NASA’s Kepler Space Telescope orbits the Sun in concert with the Earth, slowly drifting away from Earth.Image: NASA Kepler Mission/Dana BerryResearch, Astronomy, Kavli Institute, NASA, Physics, Planetary science, Satellites, Space, astronomy and planetary science, National Science Foundation (NSF)A better device for measuring electromagnetic radiationhttp://news.mit.edu/2018/better-device-measuring-electromagnetic-radiation-0611
New bolometer is faster, simpler, and covers more wavelengths.
Mon, 11 Jun 2018 11:28:14 -0400David Chandler | MIT News Officehttp://news.mit.edu/2018/better-device-measuring-electromagnetic-radiation-0611<p>Bolometers, devices that monitor electromagnetic radiation through heating of an absorbing material, are used by astronomers and homeowners alike. But most such devices have limited bandwidth and must be operated at ultralow temperatures. Now, researchers say they’ve found a ultrafast yet highly sensitive alternative that can work at room temperature — and may be much less expensive.</p>
<p>The findings, published today in the journal <em>Nature Nanotechnology</em>, could help pave the way toward new kinds of astronomical observatories for long-wavelength emissions, new heat sensors for buildings, and even new kinds of quantum sensing and information processing devices, the multidisciplinary research team says. The group includes recent MIT postdoc Dmitri Efetov, Professor Dirk Englund of MIT’s Department of Electrical Engineering and Computer Science, Kin Chung Fong of Raytheon BBN Technologies, and colleagues from MIT and Columbia University.</p>
<p>“We believe that our work opens the door to new types of efficient bolometers based on low-dimensional materials,” says Englund, the paper’s senior author. He says the new system, based on the heating of electrons in a small piece of a two-dimensional form of carbon called graphene, for the first time combines both high sensitivity and high bandwidth — orders of magnitude greater than that of conventional bolometers — in a single device.</p>
<p>“The new device is very sensitive, and at the same time ultrafast,” having the potential to take readings in just picoseconds (trillionths of a second), says Efetov, now a professor &nbsp;at ICFO, the Institute of Photonic Sciences in Barcelona, Spain, who is the paper’s lead author. “This combination of properties is unique,” he says.</p>
<p>The new system also can operate at any temperature, he says, unlike current devices that have to be cooled to extremely low temperatures. Although most actual applications of the device would still be done under these ultracold conditions, for some applications, such as thermal sensors for building efficiency, the ability to operate without specialized cooling systems could be a real plus. “This is the first device of this kind that has no limit on temperature,” Efetov says.</p>
<p>The new bolometer they built, and demonstrated under laboratory conditions, can measure the total energy carried by the photons of incoming electromagnetic radiation, whether that radiation is in the form of visible light, radio waves, microwaves, or other parts of the spectrum. That radiation may be coming from distant galaxies, or from the infrared waves of heat escaping from a poorly insulated house.</p>
<p>The device is entirely different from traditional bolometers, which typically use a metal to absorb the radiation and measure the resulting temperature rise. Instead, this team developed a new type of bolometer that relies on heating electrons moving in a small piece of graphene, rather than heating a solid metal. The graphene is coupled to a device called a photonic nanocavity, which serves to amplify the absorption of the radiation, Englund explains.</p>
<p>“Most bolometers rely on the vibrations of atoms in a piece of material, which tends to make their response slow,” he says. In this case, though, “unlike a traditional bolometer, the heated body here is simply the electron gas, which has a very low heat capacity, meaning that even a small energy input due to absorbed photons causes a large temperature swing,” making it easier to make precise measurements of that energy. Although graphene bolometers had previously been demonstrated, this work solves some of the important outstanding challenges, including efficient absorption into the graphene using a nanocavity, and the impedance-matched temperature readout.</p>
<p>The new technology, Englund says, “opens a new window for bolometers with entirely new functionalities that could radically improve thermal imaging, observational astronomy, quantum information, and quantum sensing, among other applications.”</p>
<p>For astronomical observations, the new system could help by filling in some of the remaining wavelength bands that have not yet had practical detectors to make observations, such as the “terahertz gap” of frequencies that are very difficult to pick up with existing systems. “There, our detector could be a state-of-the-art system” for observing these elusive rays, Efetov says. It could be useful for observing the very long-wavelength cosmic background radiation, he says.</p>
<p>Daniel Prober, a professor of applied physics at Yale University who was not involved in this research, says, “This work is a very good project to utilize the many benefits of the ultrathin metal layer, graphene, while cleverly working around the limitations that would otherwise be imposed by its conducting nature.” He adds, “The resulting detector is extremely sensitive for power detection in a challenging region of the spectrum, and is now ready for some exciting applications.”</p>
<p>And Robert Hadfield, a professor of photonics at the University of Glasgow, who also was not involved in this work, says, “There is&nbsp; huge demand for new high-sensitivity infrared detection technologies. This work by Efetov and co-workers reporting an innovative graphene bolometer integrated in a photonic crystal cavity to achieve high absorption is timely and exciting.”</p>
Schematic illustration of the experimental setupImage courtesy of the researchersResearch, School of Engineering, Computer science and technology, Electrical Engineering & Computer Science (eecs), Physics, Research Laboratory of Electronics, Graphene, Carbon, AstronomyThe quantum choreographerhttp://news.mit.edu/2018/mit-alumnus-ashok-ajoy-nmr-mri-without-magnets-0611
Using diamond dust and laser light to control atomic spin, Ashok Ajoy PhD ’16 pursues alternatives to costly conventional imaging technologies.Mon, 11 Jun 2018 09:00:00 -0400Leda Zimmerman | Department of Nuclear Science and Engineeringhttp://news.mit.edu/2018/mit-alumnus-ashok-ajoy-nmr-mri-without-magnets-0611<p>Listening to&nbsp;<a href="http://web.mit.edu/ashokaj/www/" target="_blank">Ashok Ajoy</a>&nbsp;PhD ’16&nbsp;talk about his work, it’s easy to forget he’s a physicist. “I make spins dance together, go up or down, interact, in a kind of spin choreography,” he says.</p>
<p>Ajoy unleashes his creativity not on human bodies but on elementary particles, manipulating quantum behavior, and specifically, spin — the property of angular momentum intrinsic to such entities as atomic nuclei.</p>
<p>After doctoral research at MIT generating insights on spin and novel methods for maneuvering quantum mechanical objects, Ajoy is now pioneering technologies with the potential to transform the fields of imaging and chemical analysis. Using diamond dust, laser light, and water, Ajoy and his colleagues at the University of California at Berkeley are pursuing alternatives to the multi-million dollar, room-size machines in current use.</p>
<p>“Our vision is to achieve conventional magnetic resonance imaging&nbsp;at a fraction of the cost and to revolutionize industries that rely on nuclear magnetic resonance&nbsp;to study molecules, such as pharmaceutical companies,” he says.</p>
<p>These emerging technologies reflect Ajoy’s lifelong passion not just for understanding how things work, but for crafting things that work better. Growing up in Bangalore, Ajoy says he “learned that building something and making a mess is fun.” His dad, “a gizmo freak,” found ways to use parts intended for other applications, like building a revolving table from a washing machine rotor. “He was really creative, and while I didn't acquire his genes, he really inspired me,” says Ajoy.</p>
<p>In college, Ajoy secured the key to the physics lab, where he “hung out the entire night, trying to make signal generators and other basic instrumentation on the cheap.” It was here that his fascination for quantum engineering crystallized. He wanted to build his&nbsp;own version of an nuclear magnetic resonance (NMR) machine, a spectroscopy instrument that could function without the expensive magnet.</p>
<p>Ajoy’s ambition was to leapfrog technology launched at MIT after World War II.</p>
<p>“Using equipment lying around in the radar lab, scientists saw that by shining radiofrequency — electromagnetic radiation — on water, they could produce a signal from deep inside the nucleus of hydrogen atoms," says Ajoy.</p>
<p>That&nbsp;was the birth of NMR and magnetic resonance imaging (MRI). This signal, generated when nuclei in hydrogen atoms align in the presence of a magnetic field (a manifestation of quantum mechanical spin) sparked new imaging technology. With MRI and NMR, magnets generate an imbalance in spin orientation of hydrogen nuclei in water molecules, and machines read that imbalance. As this technology has matured over decades, the size and strength of the magnets has grown, with some NMR machines used for molecular analysis occupying entire building floors.</p>
<p>It was not until Ajoy arrived at MIT for doctoral work in nuclear science and engineering that he was able to delve directly into the spin physics that pointed toward a magnet-free approach to imaging. He found research freedom and support in the lab of&nbsp;<a href="http://Paola Cappellaro" target="_blank">Paola Cappellaro</a>, the Esther and Harold Edgerton Associate Professor of Nuclear Science and Engineering.</p>
<p>“Paola was an incredible advisor. She gave me creative license to build something from scratch,” says Ajoy. “At MIT I found the encouragement to work on ideas that others had not before.”</p>
<p>With Cappellaro’s Quantum Engineering group, Ajoy exploited a spin system found in the atomic lattice of pink diamonds, in which a single nitrogen atom replaces a carbon atom. This is called a nitrogen vacancy (NV) center. In response to carbon atoms, the two electrons on the nitrogen atom become one&nbsp;“with very nice properties,” says Ajoy. “With just the light of a green laser pointer, you can control the spin state of this electron, making the spins do precisely what you want.”</p>
<p>Before experimental work, Ajoy spent several years theoretically modeling NV center ideas, which he published in a series of journal articles; “One paper garnered attention, because it made a compelling proposal that using light, not large magnetic fields, we could create sensors from our NV spin system to determine the structure of a single molecule.”</p>
<p>Discerning molecular structure molecule is essential to making new compounds, including&nbsp;drugs. While X-ray crystallography and NMR can accomplish this feat, these techniques are limited since&nbsp;not all molecules can be crystallized for X-ray imaging&nbsp;and NMR requires large samples of a substance to image.</p>
<p>When Ajoy finally got his chance to build a machine to test his theories, he says:&nbsp;“We were short on resources, so we planned it down to the last mirror,” he says. His experimental findings, demonstrating a method for extremely high resolution, NV-center nanoscale imaging, proved nonetheless groundbreaking, and were&nbsp;<a href="http://arxiv.org/abs/1604.01677" target="_blank">published in&nbsp;<em>Proceedings of the National Academy of Sciences</em>.</a></p>
<p>Ajoy's doctoral work earned him&nbsp;the department’s 2017 Del Favero Thesis Prize. It also drew the attention of Alexander Pines, Glenn T. Seaborg Professor of Chemistry at Berkeley, who invited Ajoy to lead a 20-person team to exploit diamond spins for new applications.</p>
<p>His group is rapidly advancing into new territory, including crushing pink diamonds into dust to increase the surface area of a spin-based imaging device, so that even a tiny amount of light can align the spins. The next goal is to flow water through a device containing optically polarized diamond dust, creating polarized liquid.</p>
<p>“It’s like science fiction, because you could take this activated water, which is perfectly safe, and inject it into a body, creating an MRI picture that's 100 times brighter than conventional MRI,” says Ajoy. “For the cost of perhaps the front display used in a $3 million dollar magnetic imaging machine, you could build our instrument.”</p>
<p>This vision is swiftly moving beyond the realm of science fiction. Over the course of four months, Ajoy's team constructed a prototype imaging device a bit bigger than an iPhone for $3,000. If the group can polarize liquid with it, they will have an inexpensive, portable imaging instrument perfect for wide-ranging medical applications.</p>
<p>“It will be proof that quantum technologies really work, and that it is possible to create something both visionary and tangible in a relatively short time,” says Ajoy. ”It feels incredible to be pushing the boundaries of human knowledge.”</p>
Ashok Ajoy PhD ’16, poses with a prototype hyperpolarizer device.Photo courtesy of Emanuel Druga and John Fyson.Research, Graduate, postdoctoral, Nuclear science and engineering, Physics, Sensors, Nanoscience and nanotechnology, School of Engineering, Imaging, Profile, Alumni/ae3 Questions: Pinning down a neutrino’s masshttp://news.mit.edu/2018/3-questions-pinning-down-neutrino-mass-0611
KATRIN experiment investigates the ghostly particle.Fri, 08 Jun 2018 15:58:23 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/3-questions-pinning-down-neutrino-mass-0611<p><em>Neutrinos are everywhere, and yet their presence is rarely felt. Scientists have assumed for decades that, because they interact so little with matter, neutrinos must lack any measurable mass. But recent experiments have shown that these “ghostly” particles do in fact hold some weight. Ever since, the hunt has been on to pin down a neutrino’s mass — a vanishingly small measurement that could have huge implications for our understanding of how the universe has evolved. </em></p>
<p><em>Today, a major experiment has joined this fundamental search. The Karlsruhe Tritium Neutrino Experiment, or KATRIN, is a massive detector based in the town of Karlsruhe, Germany, that has been designed to measure a neutrino’s mass with far greater precision than existing experiments. At KATRIN’s heart is a 200-ton, zeppelin-like spectrometer, and scientists hope that with the experiment launching today they can start to collect data that in the next few years will give them a better idea of just how massive neutrinos can be. </em></p>
<p><em>Professor of physics Joseph Formaggio is part of the team of scientists that will get a first look at KATRIN’s data as they come in. Formaggio and others from MIT helped construct part of the detector’s apparatus and developed software to simulate the trajectory of particles passing through the detector. His group is now working along with a team of scientists around the world on software to analyze the data for signs of neutrino mass. </em>MIT News<em> sat down with Formaggio ahead of the experiment’s launch, for a chat about KATRIN and the monumental structure built to search for an infinitesimal signal. &nbsp;</em></p>
<p><strong>Q: </strong>How will KATRIN measure the mass of a neutrino?</p>
<p><strong>A:</strong> KATRIN is addressing a very old question, one that was posed by [Enrico] Fermi in the 1930s, which is the question of how much mass a neutrino has. Decades ago, we thought the neutrino had to be massless. Then experiments in neutrino oscillations showed that no, that wasn’t actually true — neutrinos actually have a tiny mass. And now we know that different neutrinos have different masses from each other. What we don’t know is how much any one neutrino weighs — the absolute mass is still unknown.</p>
<p>KATRIN addresses this question by looking at energy conservation: E = mc<sup>2</sup>. We have a radioactive gas, in this case, tritium, that releases energy as it decays. Some of that energy goes to a neutrino, which flies off and we never see it again. Some of that energy goes to an electron, and if you measure the electron’s energy very precisely, it turns out that tells you how much the neutrino took away. And in particular, was that energy all kinetic, because the neutrino was going away at the speed of light? Or does it have a little bit of rest energy, or mass?</p>
<p>The experiment itself is about 70 meters long — almost a football field but not quite. Tritium is injected at one end, into a windowless tube, where there are millions of decays happening per second, all of which will produce electrons. The gas sits inside a magnet, and the electrons, because they’re charged, see this magnetic field, and they begin to follow the magnetic field lines out of the gas region and into a huge spectrometer — one of the largest vacuums in the world. The magnetic field is very weak in the spectrometer, and the field lines will start to spread out. The spectrometer is held at an electric potential of nearly 20,000 volts, which acts like a hill: Electrons that have enough energy will make it over this hill and come out the other side of the spectrometer. The ones that don’t have enough energy get turned back.</p>
<p>Then there’s another set of magnets at the very end of this long beam line, where the field lines get tighter, the electrons focus back in, and they land on a detector that just counts electrons. This is a very precise way of scanning electron energies from this very hot, radioactive source. And that’s what allows us to get the energy resolution we need, to say something about neutrino mass.</p>
<p><strong>Q: </strong>What is the current estimate for a neutrino’s mass, and how will you know you’ve reached an even more precise measurement?</p>
<p><strong>A:</strong> We have some idea of what the neutrino mass scale should be. Previous experiments have told us that it’s somewhere between 10 millielectronvolts and 2 electronvolts. An electron, which is the other lightest particle that we know about, has a mass of about 511,000 electronvolts. So somewhere between 10 meV and 2eV is our playground.</p>
<p>If the neutrino does have a mass, what does it look like in our experiment? What we do is we image the spectrum of electron energies. If the neutrino has a mass, it looks like a kink in our spectrum. So we look for that kink, which would mean that the neutrino has both kinetic energy, which we expect, but also rest energy. If it were all kinetic, then it has no mass, and it’s zipping along at the speed of light. If you observe a kink, it’s as if you made a neutrino that stood still. Things can’t stay still if they are massless. The kink is evidence that you produce just a few neutrinos that were standing still. You didn’t see them directly, but you saw the electron didn’t take the energy that it was supposed to, and that energy went into the neutrino.</p>
<p><strong>Q: </strong>In what ways would a more precise neutrino mass change our understanding of the universe?</p>
<p><strong>A:</strong> For other particles like the top quark and the electron, we might not understand why they have the masses they do, but we understand how they have mass. For the neutrino, that’s an open question. How the neutrino gets its mass is unknown. The hope is, by measuring the mass of the neutrino, you get a better sense of how a neutrino gets its mass. We have billions of neutrinos everywhere in the universe. If all of a sudden they have a mass, they will impact how the universe will evolve over time. For cosmologists, that information will be very useful.</p>
<p>So there’s a little bit of, what’s going to happen when we actually make a measurement? Will we see something massive? There is a possibility for surprise, and that could be most exciting, because it would mean we really don’t understand what we’re doing, and that’s usually good for us.</p>
<p>This is a long experiment coming. I joined the experiment when I was a postdoc in 2003, and there were people thinking about it even before then. It’s taken a long time, and it’s an incredible marvel of engineering. Because each time, they’ve had to solve a problem that didn’t have a solution yet. How do you build a tank of that size, and evacuate it so that it’s in vacuum? The tank is empty. Of air! And it’s a huge tank, one of the largest vacuums in the world. That’s an engineering feat. How do you keep the radioactive gas cold and stable to a few millikelvin? All these things really took a lot of engineering, and it’s a beautiful experiment. Now we get to take data, and that’s going to be very exciting.</p>
The Karlsruhe Tritium Neutrino Experiment, or KATRIN, is a massive detector based in the town of Karlsruhe, Germany, that has been designed to measure a neutrino’s mass with far greater precision than existing experiments.Image: Karlsruhe/KIT Katrin3 Questions, Neutrinos, Physics, Research, Laboratory for Nuclear Science, School of ScienceQS ranks MIT the world’s No. 1 university for 2018-19http://news.mit.edu/2018/qs-ranks-mit-worlds-no-1-university-2018-19-0606
Ranked at the top for the seventh straight year, the Institute also places first in 12 of 48 disciplines.Wed, 06 Jun 2018 16:00:00 -0400MIT News Officehttp://news.mit.edu/2018/qs-ranks-mit-worlds-no-1-university-2018-19-0606<p>For the seventh year in a row MIT has topped the QS World University Rankings, which were announced today.</p>
<p>The full 2018-19 rankings — published by Quacquarelli Symonds, an organization specializing in education and study abroad — can be found at <a href="https://www.topuniversities.com/qs-world-university-rankings">topuniversities.com</a>. The QS rankings were based on academic reputation, employer reputation, citations per faculty, student-to-faculty ratio, proportion of international faculty, and proportion of international students. MIT earned a perfect overall score of 100.</p>
<p>MIT was also ranked the world’s top university in <a href="http://news.mit.edu/2018/mit-no-1-2018-qs-world-university-rankings-subjects-0228">12 of 48 disciplines ranked by QS</a>, as announced in February of this year.</p>
<p>MIT received a No. 1 ranking in the following QS subject areas: Architecture/Built Environment; Linguistics; Chemical Engineering; Civil and Structural Engineering; Computer Science and Information Systems; Electrical and Electronic Engineering; Mechanical, Aeronautical and Manufacturing Engineering; Chemistry; Materials Science; Mathematics; Physics and Astronomy; and Statistics and Operational Research. &nbsp;&nbsp;</p>
<p>Additional high-ranking MIT subjects include: Art and Design (No. 4), Biological Sciences (No. 2), Earth and Marine Sciences (No. 3), Environmental Sciences (No. 3), Accounting and Finance (No. 2), Business and Management Studies (No. 4), and Economics and Econometrics (No. 2).</p>
Photo: AboveSummit with Christopher HartingRankings, Architecture, Chemical engineering, Chemistry, Civil and environmental engineering, Electrical Engineering & Computer Science (eecs), Economics, Linguistics, Materials Science and Engineering, DMSE, Mechanical engineering, Aeronautical and astronautical engineering, Physics, Business and management, Accounting, Finance, Arts, Design, Mathematics, EAPS, School of Architecture and Planning, School of Humanities Arts and Social Sciences, School of Science, School of Engineering, Sloan School of ManagementQuantum physics student leaving MIT on a high notehttp://news.mit.edu/2018/quantum-physics-senior-shaun-datta-leaving-mit-on-high-note-0605
Math and physics major Shaun Datta wraps up four years of pushing himself beyond his comfort zone by singing a cappella with the MIT Logarhythms. Tue, 05 Jun 2018 16:45:00 -0400Sandi Miller | Department of Mathematicshttp://news.mit.edu/2018/quantum-physics-senior-shaun-datta-leaving-mit-on-high-note-0605<p>On the Friday before finals, the crowd in Kresge Auditorium awaited the last <a href="http://www.mitlogs.com./" target="_blank">MIT Logarhythms</a>’ performance of the year. Along the side of the stage, the 16 male singers yell “Logs on three … one, two, three … Logs on three!” and then run, jump and leap into view. Although they can’t see the audience beyond the lights, they feed off the crowd’s energy as they harmonize a capella.</p>
<p>At the end of the night, the group sang “Climax” by Usher, featuring senior Shaun Datta, who has been singing with the group since his freshman year. Datta chose “Climax,” not just because it’s a song about saying goodbye, but because it stretched his range — something that his time with the Logarhythms helped him to do in his life outside the group.</p>
<p>“I wanted to sing something where I was floating some parts because it’s pretty high,” Datta says. “It's in an uncomfortable place in the male register. Even after singing it for a few months now, it’s still a little uncomfortable to sing, which is what I wanted: a song that was unfamiliar territory.”</p>
<p><strong>Growing up STEM</strong></p>
<p>Before the Logarhythms, Datta only made a little time for singing. He had been focused on his education in science his entire life. As the son of a psychologist and a chemical engineer, he was taught “algebra and geometry at the dinner table before my legs were long enough to reach the floor.”</p>
<p>At Montgomery Blair High School in Silver Spring, Maryland, he was in the mathematics, science, and computer science core, with electives that included quantum physics, organic chemistry, and complex variables. He also published a paper in <em>Physical Review</em> via the University of Maryland.&nbsp;</p>
<p>When Datta was considering which college to attend, MIT stood out as an excellent place to pursue his interests, which at the time he described as “the interface of natural sciences and computation, particularly quantum computation and computational biology.” But the deciding factor was how MIT students pursued their interests.</p>
<p>“When I went to visit the schools, there was a marked difference between MIT and everywhere else,” he says. “Many clever students go through the motions of the college application process and end up with a carefully manicured résumé but no clear sense of passion. What set MIT apart for me was that everyone is passionate about something. You can see it in the ways students spend their time outside of academics: tinkering, hacking, making music, all from their untampered passion. I wanted to be a part of that culture.”</p>
<p><strong>Making time for music</strong></p>
<p>Once at MIT, Datta would double-major in physics and mathematics with computer science, with a concentration in negotiation and leadership. Although schoolwork was consuming, he would find time for involvement in many activities at the Institute and beyond. He was a policy advisor and voting member with the MIT Committee on Undergraduate Program; an associate academic advisor for the Mathematical Problem-Solving Seminar; an MIT student ambassador; the designer of a new Negotiation and Leadership program alongside Professor Bruno Verdini; and an organizer of the 2016 MIT-Harvard Undergraduate Physics Conference as MIT Society of Physic Students' Secretary and Outreach Coordinator. During breaks he attended University of Waterloo’s two-week summer program that focused on the theoretical and experimental study of quantum information, and a teacher in the SPLASH program and <a href="http://misti.mit.edu/senior-shaun-datta-teaches-physics-and-maths-barcelona-spain" target="_blank">in Barcelona</a>. In the fall, he collaborated with Belgian lecturer <a href="http://felicitasrohden.com/" target="_blank">Felicitas Rohden</a> for her German <a href="https://www.kunstunddenker.com/artists/#/felicitas-rohden/" target="_blank">art installation</a> that visually explained quantum information.</p>
<p>When he first came across the Logarhythms’ information table as a freshman, he saw it as a good way to make friends. But it also turned out to be time-consuming: In addition to six hours of rehearsal a week with group and more time on his own, there were performances, competitions, and even an <a href="https://mitlogs.com/discography/as-viewed-from-above-2016/" target="_blank">album recording</a>.</p>
<p>But ultimately, Datta’s commitment to the Logarhythms helped him structure his time better and, more importantly, formed a counterpoint to the stress of academic pursuits. As soon as he entered the Logs’ practice space or climbed onstage, he easily switched gears from busy student to singer.</p>
<p>“Usually I’m quite focused on the music, and generally engaged with the feel of the music,” Datta said. “We try to leave the rest of our thoughts and distractions at the door, so we can be very focused, and to give us a reprieve from the other things we’re working on.”</p>
<p><strong>Logging out</strong></p>
<p>After graduation, Datta wants to build a career in quantum physics. He has received a $138,000 National Science Foundation Graduate Research Fellowship, and will choose between a DAAD scholarship at the Technische Universität München or attending one of the programs at Cambridge University. He is also considering working for a while at first and to start writing a book about the history of string theory. As he decides, he’ll spend this summer in an exchange program with a grant from the Department of Energy and National Institute for Nuclear Physics in Italy to search for dark matter candidates via machine learning at Frascati National Laboratory.&nbsp;</p>
<p>As for singing, he eventually hopes to return to the stage, whether it be via a coffeehouse solo or another a capella group. He also will join the Logarhythms’ extensive alumni network, the most active of whom attend performances and help with song arrangements.</p>
<p>As Datta nears graduation, he’s having trouble believing that his time with the Logarhythms is over.</p>
<p>“The Logs has been the utmost formative experience of my college education,” he says.</p>
“The Logs has been the utmost formative experience of my college education,” says MIT senior Shaun Datta, at center performing with his fellow MIT Logarhythms. “We try to leave the rest of our thoughts and distractions at the door, so we can be very focused, and to give us a reprieve from the other things we’re working on.”Photo: Vincent TjengStudents, Profile, Undergraduate, Mathematics, Physics, Student life, MISTI, International initiatives, Music, Quantum computing, School of Science, School of Humanities Arts and Social SciencesMeet the School of Science’s tenured professors for 2018http://news.mit.edu/2018/meet-school-of-science-tenured-professors-0604
Six faculty members are granted tenure in four departments. Mon, 04 Jun 2018 13:00:01 -0400Bendta Schroeder | School of Sciencehttp://news.mit.edu/2018/meet-school-of-science-tenured-professors-0604<p>The School of Science has announced that six members of its faculty have been granted tenure by MIT.</p>
<p>This year’s newly tenured associate professors are:</p>
<p><a href="http://cziczogroup.scripts.mit.edu/wp/" target="_blank">Daniel Cziczo</a> studies the interrelationship of atmospheric aerosol particles and cloud formation and its impact on the Earth’s climate system. Airborne particles can impact climate directly by absorbing or scattering solar and terrestrial radiation and indirectly by acting as the seeds on which cloud droplets and ice crystals form. Cziczo’s experiments include using small cloud chambers in the laboratory to mimic atmospheric conditions that lead to cloud formation and observing clouds in situ from remote mountaintop sites or through the use of research aircraft.</p>
<p>Cziczo earned a BS in aerospace engineering from the University of Illinois at Urbana-Champaign in 1992, and afterwards spent two years at the NASA Jet Propulsion Laboratory performing spacecraft navigation. Cziczo earned a PhD in geophysical sciences in 1999 from the University of Chicago under the direction of John Abbatt. Following research appointments at the Swiss Federal Institute of Technology and then the Pacific Northwest National Laboratory, where he directed the Atmospheric Measurement Laboratory, Cziczo joined the MIT faculty in the Department of Earth, Atmospheric and Planetary Sciences in 2011.</p>
<p><a href="http://web.mit.edu/physics/people/faculty/evans_matthew.html" target="_blank">Matthew Evans</a> focuses on gravitational wave detector instrument science, aiming to improve the sensitivity of existing detectors and designing future detectors. In addition to his work on the Advanced the Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors, Evans explores the physical processes that set fundamental limits on the sensitivity of future gravitational wave detectors. Of particular interest are the quantum and thermal limitations which have the strongest impact on ground-based detectors like LIGO and also play a role in the related fields of ultra-stable frequency references and macroscopic quantum measurement.</p>
<p>Evans received a BS in physics from Harvey Mudd College in 1996 and a PhD from Caltech in 2002. After postdoctoral work on LIGO at Caltech, Evans moved to the European Gravitational Observatory to work on the Virgo project. In 2007, he took a research scientist position at MIT working on the Advanced LIGO project, where he helped design and build its interferometer. He joined the MIT faculty in the Department of Physics in 2013.</p>
<p><a href="http://web.mit.edu/physics/people/faculty/frebel_anna.html" target="_blank">Anna Frebel</a> studies the chemical and physical conditions of the early universe, and how the oldest, still-surviving stars can be used to obtain constraints on the nature of the very first stars and early supernova explosions, and associated stellar element nucleosynthesis. She is best known for her discoveries and subsequent spectroscopic analyses of 13 billion-year-old stars in the Milky Way and ancient faint stars in the least luminous dwarf galaxies, to uncover unique information about the physical and chemical conditions of the early Universe. With this work, she has been able to obtain a more comprehensive view of the formation of our Milky Way Galaxy with its extended stellar halo because the formation history of each galaxy is imprinted in the chemical signatures of its stars. To extract this information, Frebel is also involved in a large supercomputing project that simulates the formation and evolution of large galaxies like the Milky Way.&nbsp;</p>
<p>Frebel received her PhD from the Australian National University in 2007. After a W. J. McDonald Postdoctoral Fellowship at the University of Texas at Austin, she completed a Clay Postdoctoral Fellowship at the Harvard-Smithsonian Center for Astrophysics in 2009. Frebel joined the MIT faculty in the Department of Physics in 2012.</p>
<p><a href="http://www.mit.edu/~aram/" target="_blank">Aram Harrow</a> works to understand the capabilities of the quantum computers and quantum communication devices and in the process creates connections to other areas of theoretical physics, mathematics, and computer science. As a graduate student, Harrow developed the idea of "coherent classical communication," which along with his work on the resource inequality method, has greatly simplified the understanding of quantum information theory. Harrow has also produced foundational work on the role of representation theory in quantum algorithms and quantum information theory. In 2008, Harrow, Hassidim, and Lloyd developed a quantum algorithm for solving linear systems of equations that provides a rare example of an exponential quantum speedup for a practical problem. Recently Harrow has been investigating properties of entanglement, such as approximate "superselection" and "monogamy" principles with the goal of better understanding not only entanglement and its uses, but also the related areas of quantum communication, many-body physics, and convex optimization.</p>
<p>Harrow received his undergraduate degree in 2001 and his PhD in 2005 from MIT. After his PhD, he spent five years as a lecturer at the University of Bristol and then two years as a research assistant professor at the University of Washington. Harrow returned to MIT to join the faculty in the Department of Physics in 2013.&nbsp;</p>
<p><a href="http://web.mit.edu/martin-lab/">Adam Martin</a> studies how cells and tissues change shape during embryonic development, giving rise to organs with distinct shapes and structure. He has developed a system to visualize and quantify the movement of molecules, cells, and tissues during tissue folding in the fruit fly early embryo, where cells and motor proteins within these cells can be readily imaged by confocal microscopy on the time scale of seconds. Tissue folding in the fruit fly involves conserved genes that also function to form the mammalian neural tube, which gives rise to the mammalian brain and spinal cord. Martin combines live imaging with genetic, cell biological, computational, and biophysical approaches to dissect the molecular and cellular mechanisms that sculpt tissues. In addition, the lab examines how tissues grow and are remodeled during development, investigating processes such as cell division and the epithelial-mesenchymal transition.</p>
<p>After Martin received a BS in biology from Cornell University in 2000, he completed his PhD in molecular and cell biology under the direction of David Drubin and Matthew Welch at the University of California at Berkeley in 2006. After a postdoctoral fellowship at Princeton University in the laboratory of Eric Weischaus, Martin joined the MIT faculty in the Department of Biology in 2011.</p>
<p><a href="https://tyelab.mit.edu/">Kay Tye</a> dissects the synaptic and cellular mechanisms in emotion and reward processing with the goal of understanding how they underpin addiction-related behaviors and frequently co-morbid disease states such as attention-deficit disorder, anxiety, and depression. Using an integrative approach including optogenetics, pharmacology, and both in vivo and ex vivo electrophysiology, she explores such problems as how neural circuits differently encode positive and negative cues from the environment; if and how perturbations in neural circuits mediating reward processing, fear, motivation, memory, and inhibitory control underlie the co-morbidity of substance abuse, attention-deficit disorder, anxiety, and depression; and how emotional states such as increased anxiety might increase the propensity for substance abuse by facilitating long-term changes associated with reward-related learning.</p>
<p>Tye received her BS in brain and cognitive sciences from MIT in 2003 and earned her PhD in 2008 at the University of California at San Francisco under the direction of Patricia Janak. After she completed her postdoctoral training with Karl Deisseroth at Stanford University in 2011, she returned to the MIT Department of Brain and Cognitive Sciences as a faculty member in 2012.</p>
Newly tenured professors in the School of Science (clockwise from top left): Daniel Cziczo, Matthew Evans, Anna Frebel, Aram Harrow, Adam Martin, and Kay Tye.Faculty, School of Science, Biology, Physics, EAPS, Brain and cognitive sciences, Kavli Institute, Picower InstituteResearchers devise new way to make light interact with matterhttp://news.mit.edu/2018/researchers-devise-new-way-make-light-interact-matter-0604
Reducing the wavelength of light could allow it to be absorbed or emitted by a semiconductor, study suggests. Mon, 04 Jun 2018 11:00:00 -0400David L. Chandler | MIT News Officehttp://news.mit.edu/2018/researchers-devise-new-way-make-light-interact-matter-0604<p>A new way of enhancing the interactions between light and matter, developed by researchers at MIT and Israel’s Technion, could someday lead to more efficient solar cells that collect a wider range of light wavelengths, and new kinds of lasers and light-emitting diodes (LEDs) that could have fully tunable color emissions.</p>
<p>The fundamental principle behind the new approach is a way to get the momentum of light particles, called photons, to more closely match that of electrons, which is normally many orders of magnitude greater. Because of the huge disparity in momentum, these particles usually interact very weakly; bringing their momenta closer together enables much greater control over their interactions, which could enable new kinds of basic research on these processes as well as a host of new applications, the researchers say.</p>
<p>The new findings, based on a theoretical study, are being published today in the journal <em>Nature Photonics</em> in a paper by Yaniv Kurman of Technion (the Israel Institute of Technology, in Haifa); MIT graduate student Nicholas Rivera; MIT postdoc Thomas Christensen; John Joannopoulos, the Francis Wright Davis Professor of Physics at MIT; Marin Soljačić, professor of physics at MIT; Ido Kaminer, a professor of physics at Technion and former MIT postdoc; and Shai Tsesses and Meir Orenstein at Technion.</p>
<p>While silicon is a hugely important substance as the basis for most present-day electronics, it is not well-suited for applications that involve light, such as LEDs and solar cells — even though it is currently the principal material used for solar cells despite its low efficiency, Kaminer says. Improving the interactions of light with an important electronics material such as silicon could be an important milestone toward integrating photonics — devices based on manipulation of light waves — with electronic semiconductor chips.</p>
<p>Most people looking into this problem have focused on the silicon itself, Kaminer says, but “this approach is very different — we’re trying to change the light instead of changing the silicon.” Kurman adds that “people design the matter in light-matter interactions, but they don’t think about designing the light side.”</p>
<p>One way to do that is by slowing down, or shrinking, the light enough to drastically lower the momentum of its individual photons, to get them closer to that of the electrons. In their theoretical study, the researchers showed that light could be slowed by a factor of a thousand by passing it through a kind of multilayered thin-film material overlaid with a layer of graphene. The layered material, made of gallium arsenide and indium gallium arsenide layers, alters the behavior of photons passing through it in a highly controllable way. This enables the researchers to control the frequency of emissions from the material by as much as 20 to 30 percent, says Kurman, who is the paper’s lead author.</p>
<p>The interaction of a photon with a pair of oppositely charged particles — such as an electron and its corresponding “hole” — produces a quasiparticle called a plasmon, or a plasmon-polariton, which is a kind of oscillation that takes place in an exotic material such as the two-dimensional layered devices used in this research. Such materials “support electromagnetic oscillations on its surface, really tightly confined” within the material, Rivera says. This process effectively shrinks the wavelengths of light by orders of magnitude, he says, bringing it down “almost to the atomic scale.”</p>
<p>Because of that shrinkage, the light can then be absorbed by the semiconductor, or emitted by it, he says. In the graphene-based material, these properties can actually be controlled directly by simply varying a voltage applied to the graphene layer. In that way, “we can totally control the properties of the light, not just measure it,” Kurman says.</p>
<p>Although the work is still at an early and theoretical stage, the researchers say that in principle this approach could lead to new kinds of solar cells capable of absorbing a wider range of light wavelengths, which would make the devices more efficient at converting sunlight to electricity. It could also lead to light-producing devices, such as lasers and LEDs, that could be tuned electronically to produce a wide range of colors. “This has a measure of tunability that’s beyond what is currently available,” Kaminer says.</p>
<p>“The work is very general,” Kurman says, so the results should apply to many more cases than the specific ones used in this study. “We could use several other semiconductor materials, and some other light-matter polaritons.” While this work was not done with silicon, it should be possible to apply the same principles to silicon-based devices, the team says. “By closing the momentum gap, we could introduce silicon into this world” of plasmon-based devices, Kurman says.</p>
<p>Because the findings are so new, Rivera says, it “should enable a lot of functionality we don’t even know about yet.”</p>
<p>Frank Koppens, a professor of physics at the the Institute of Photonic Sciences in Barcelona, who was not involved in this research, says “the quality of this work is very high, and quite an ‘out-of-the-box’ result.” He adds that this work is “highly significant, as it is a clear break with the conventional view on emitter-light interactions.” Since the work so far is theoretical, he says, “the main question will be if this effect is visible in experiments. I’m convinced it will be shown soon, though.”</p>
<p>Koppens says that “one can envision many applications, such as more efficient light emitters, solar cells, photodetectors etc. All integrated on a chip! It’s also a new way to control the color of a light emitter, and I’m sure there will be applications that we didn’t even think of.”</p>
<p>The work was supported by MIT’s MISTI Israel program.</p>
Researchers at MIT and Israel's Technion used a thin-film material composed of layers of gallium-arsenide and indium-gallium-arsenide, overlaid with a layer of graphene, as shown in this diagram, to produce strong interactions between light and particles that could someday enable highly tunable lasers or LEDs.
Courtesy of the researchersResearch, School of Science, Physics, Light, Energy, Photonics, Nanoscience and nanotechnology, MISTI, Israel, School of Humanities Arts and Social SciencesAI-based method could speed development of specialized nanoparticleshttp://news.mit.edu/2018/ai-based-method-could-speed-development-specialized-nanoparticles-0601
Neural network could expedite complex physics simulations.Fri, 01 Jun 2018 14:00:00 -0400David L. Chandler | MIT News Officehttp://news.mit.edu/2018/ai-based-method-could-speed-development-specialized-nanoparticles-0601<p>A new technique developed by MIT physicists could someday provide a way to custom-design multilayered nanoparticles with desired properties, potentially for use in displays, cloaking systems, or biomedical devices. It may also help physicists tackle a variety of thorny research problems, in ways that could in some cases be orders of magnitude faster than existing methods.</p>
<p>The innovation uses computational neural networks, a form of artificial intelligence, to “learn” how a nanoparticle’s structure affects its behavior, in this case the way it scatters different colors of light, based on thousands of training examples. Then, having learned the relationship, the program can essentially be run backward to design a particle with a desired set of light-scattering properties — a process called inverse design.</p>
<p>The findings are being reported in the journal<em> Science Advances</em>, in a paper by MIT senior John Peurifoy, research affiliate Yichen Shen, graduate student Li Jing, professor of physics Marin Soljačić, and five others.</p>
<p>While the approach could ultimately lead to practical applications, Soljačić says, the work is primarily of scientific interest as a way of predicting the physical properties of a variety of nanoengineered materials without requiring the computationally intensive simulation processes that are typically used to tackle such problems.</p>
<p>Soljačić says that the goal was to look at neural networks, a field that has seen a lot of progress and generated excitement in recent years, to see “whether we can use some of those techniques in order to help us in our physics research. So basically, are computers ‘intelligent’ enough so that they can do some more intelligent tasks in helping us understand and work with some physical systems?”</p>
<p>To test the idea, they used a relatively simple physical system, Shen explains. “In order to understand which techniques are suitable and to understand the limits and how to best use them, we [used the neural network] on one particular system for nanophotonics, a system of spherically concentric nanoparticles.” The nanoparticles are layered like an onion, but each layer is made of a different material and has a different thickness.</p>
<p>The nanoparticles have sizes comparable to the wavelengths of visible light or smaller, and the way light of different colors scatters off of these particles depends on the details of these layers and on the wavelength of the incoming beam. Calculating all these effects for nanoparticles with many layers can be an intensive computational task for many-layered nanoparticles, and the complexity gets worse as the number of layers grows.</p>
<p>The researchers wanted to see if the neural network would be able to predict the way a new particle would scatter colors of light — not just by interpolating between known examples, but by actually figuring out some underlying pattern that allows the neural network to extrapolate.</p>
<p>“The simulations are very exact, so when you compare these with experiments they all reproduce each other point by point,” says Peurifoy, who will be an MIT doctoral student next year. “But they are numerically quite intensive, so it takes quite some time. What we want to see here is, if we show a bunch of examples of these particles, many many different particles, to a neural network, whether the neural network can develop ‘intuition’ for it.”</p>
<p>Sure enough, the neural network was able to predict reasonably well the exact pattern of a graph of light scattering versus wavelength — not perfectly, but very close, and in much less time. The neural network simulations “now are much faster than the exact simulations,” Jing says. “So now you could use a neural network instead of a real simulation, and it would give you a fairly accurate prediction. But it came with a price, and the price was that we had to first train the neural network, and in order to do that we had to produce a large number of examples.”</p>
<p>Once the network is trained, though, any future simulations would get the full benefit of the speedup, so it could be a useful tool for situations requiring repeated simulations. But the real goal of the project was to learn about the methodology, not just this particular application. “One of the main reasons why we were interested in this particular system was for us to understand these techniques, rather than just to simulate nanoparticles,” Soljačić says.</p>
<p>The next step was to essentially run the program in reverse, to use a set of desired scattering properties as the starting point and see if the neural network could then work out the exact combination of nanoparticle layers needed to achieve that output.</p>
<p>“In engineering, many different techniques have been developed for inverse design, and it is a huge field of research,” Soljačić says. “But very often in order to set up a given inverse design problem, it takes quite some time, so in many cases you have to be an expert in the field and then spend sometimes even months setting it up in order to solve it.”</p>
<p>But with the team’s trained neural network, “we didn't do any special preparation for this. We said, ‘ok, let’s try to run it backward.’ And amazingly enough, when we compare it with some other more standard inverse design methods, this is one of the best ones,” he says. “It will actually do it much quicker than a traditional inverse design.”</p>
<p>Co-author Shen says “the initial motivation we had to do this was to set up a general toolbox that any generally well-educated person who isn’t an expert in photonics can use. … That was our original motivation, and it clearly works pretty well for this particular case.”</p>
<p>The speedup in certain kinds of inverse design simulations can be quite significant. Peurifoy says “It's difficult to have apples-to-apples exact comparisons, but you can effectively say that you have gains on the order of hundreds of times. So the gain is very very substantial — in some cases it goes from days down to minutes.”</p>
<p>The research was supported by the National Science Foundation, the Semiconductor Research Corporation, and the U.S. Army Research Office through the Institute for Soldier Nanotechnologies. Other people involved in the work are: Yi Yang, Fidel Cano-Renteria, John D. Joannopoulos, and Max Tegmark, all from MIT; and Brendan G. Delacy from U.S. Army Edgewood Chemical Biological Center.</p>
This cloaking grenade, used for hiding troop operations from view on the battlefield, is an example of nanoparticles that reflect a particular color of light based on their exact size and composition. New work by MIT researchers provides a way to predict the light-scattering properties of layered nanoparticles – or to design particles to match a desired type of light-scattering behavior.U.S. Air Force,Tech. Sgt. Scott T. Sturkol, from WikipediaResearch, School of Science, Physics, Energy, Light, Photonics, Nanoscience and nanotechnology, National Science Foundation (NSF), Materials Science and Engineering, Artificial intelligence, Machine learningTurning up the heat on thermoelectricshttp://news.mit.edu/2018/materials-heated-magnetic-fields-thermoelectrics-0525
New materials, heated under high magnetic fields, could produce record levels of energy, model shows.Fri, 25 May 2018 14:01:37 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/materials-heated-magnetic-fields-thermoelectrics-0525<p>Imagine being able to power your car partly from the heat that its engine gives off. Or what if you could get a portion of your home’s electricity from the heat that a power plant emits? Such energy-efficient scenarios may one day be possible with improvements in thermoelectric materials — which spontaneously produce electricity when one side of the material is heated.</p>
<p>Over the last 60 years or so, scientists have studied a number of materials to characterize their thermoelectric potential, or the efficiency with which they convert heat to power. But to date, most of these materials have yielded efficiencies that are too low for any widespread practical use.</p>
<p>MIT physicists have now found a way to significantly boost thermoelectricity’s potential, with a theoretical method that they report today in <em>Science Advances</em>. The material they model with this method is five times more efficient, and could potentially generate twice the amount of energy, as the best thermoelectric materials that exist today.</p>
<p>“If everything works out to our wildest dreams, then suddenly, a lot of things that right now are too inefficient to do will become more efficient,” says lead author Brian Skinner, a postdoc in MIT’s Research Laboratory of Electronics. “You might see in people’s cars little thermoelectric recoverers that take that waste heat your car engine is putting off, and use it to recharge the battery. Or these devices may be put around power plants so that heat that was formerly wasted by your nuclear reactor or coal power plant now gets recovered and put into the electric grid.”</p>
<p>Skinner’s co-author on the paper is Liang Fu, the Sarah W. Biedenharn Career Development Associate Professor of Physics at MIT,&nbsp;and a member of MIT’s Materials Research Laboratory.</p>
<p><strong>Finding holes in a theory</strong></p>
<p>A material’s ability to produce energy from heat is based on the behavior of its electrons in the presence of a temperature difference. When one side of a thermoelectric material is heated, it can energize electrons to leap away from the hot side and accumulate on the cold side. The resulting buildup of electrons can create a measurable voltage.</p>
<p>Materials that have so far been explored have generated very little thermoelectric power, in part because electrons are relatively difficult to thermally energize. In most materials, electrons exist in specific bands, or energy ranges. Each band is separated by a gap — a small range of energies in which electrons cannot exist. Energizing electrons enough to cross a band gap and physically migrate across a material has been extremely challenging.</p>
<p>Skinner and Fu decided to look at the thermoelectric potential of a family of materials known as topological semimetals. In contrast to most other solid materials such as semiconductors and insulators, topological semimetals are unique in that they have zero band gaps — an energy configuration that enables electrons to easily jump to higher energy bands when heated.</p>
<p>Scientists had assumed that topological semimetals, a relatively new type of material that is largely synthesized in the lab, would not generate much thermoelectric power. When the material is heated on one side, electrons are energized, and do accumulate on the other end. But as these negatively charged electrons jump to higher energy bands, they leave behind what’s known as “holes” — particles of positive charge that also pile up on the material’s cold side, canceling out the electrons’ effect and producing very little energy in the end.</p>
<p>But the team wasn’t quite ready to discount this material. <a href="https://www.nature.com/articles/ncomms12974">In an unrelated bit of research</a>, Skinner had noticed a curious effect in semiconductors that are exposed to a strong magnetic field. Under such conditions, the magnetic field can affect the motion of electrons, bending their trajectory. Skinner and Fu wondered: What kind of effect might a magnetic field have in topological semimetals?</p>
<p>They consulted the literature and found that a team from Princeton University, <a href="https://www.nature.com/articles/ncomms1969">in attempting to fully characterize a type of topological material known as lead tin selenide</a>, had also measured its thermoelectric properties under a magnetic field in 2013. Among their many observations of the material, the researchers had reported seeing an increase in thermoelectric generation, under a very high magnetic field of 35 tesla (most MRI machines, for comparison, operate around 2 to 3 tesla).</p>
<p>Skinner and Fu used properties of the material from the <a href="https://www.nature.com/articles/ncomms3696">Princeton study</a> to theoretically model the material’s thermoelectric performance under a range of temperature and magnetic field conditions.</p>
<p>“We eventually figured out that under a strong magnetic field, a funny thing happens, where you could make electrons and holes move in opposite directions,” Skinner says. “Electrons go toward the cold side, and holes toward the hot side. They work together and, in principle, you could get a bigger and bigger voltage out of the same material just by making the magnetic field stronger.”</p>
<p><strong>Tesla power</strong></p>
<p>In their theoretical modeling, the group calculated lead tin selenide’s ZT, or figure of merit, a quantity that tells you how close your material is to the theoretical limit for generating power from heat. The most efficient materials that have been reported so far have a ZT of about 2. Skinner and Fu found that, under a strong magnetic field of about 30 tesla, lead tin selenide can have a ZT of about 10 — five times more efficient than the best-performing thermoelectrics.</p>
<p>“It’s way off scale,” Skinner says. “When we first stumbled on this idea, it seemed a little too dramatic. It took a few days to convince myself that it all adds up.”</p>
<p>They calculate that a material with a ZT equal to 10, if heated at room temperature to about 500 kelvins, or 440 degrees Fahrenheit, under a 30-tesla magnetic field, should be able to turn 18 percent of that heat to electricity, compared to materials with a ZT equal to 2, which would only be able to convert 8 percent of that heat to energy.</p>
<p>The group acknowledges that, to achieve such high efficiencies, currently available topological semimetals would have to be heated under an extremely high magnetic field that could only be produced by a handful of facilities in the world. For these materials to be practical for use in power plants or automobiles, they should operate in the range of 1 to 2 tesla.</p>
<p>Fu says this should be doable if a topological semimetal were extremely clean, meaning that there are very few impurities in the material that would get in the way of electrons’ flow.</p>
<p>“To make materials very clean is very challenging, but people have dedicated a lot of effort to high-quality growth of these materials,” Fu says.</p>
<p>He adds that lead tin selenide, the material they focused on in their study, is not the cleanest topological semimetal that scientists have synthesized. In other words, there may be other, cleaner materials that may generate the same amount of thermal power with a much smaller magnetic field.</p>
<p>“We can see that this material is a good thermoelectric material, but there should be better ones,” Fu says. “One approach is to take the best [topological semimetal] we have now, and apply a magnetic field of 3 tesla. It may not increase efficiency by a factor of 2, but maybe 20 or 50 percent, which is already a pretty big advance.”</p>
<p>The team has filed a patent for their new thermolelectric approach and is collaborating with Princeton researchers to experimentally test the theory.</p>
<p>The research is supported by the MIT Center for Excitonics and by the Solid-State Solar Thermal Energy Conversion Center, which are Energy Frontier Research Centers of U.S. Department of Energy, and by Oﬃce of Basic Energy Sciences of U.S. Department of Energy.</p>
MIT physicists have now found a way to significantly boost thermoelectricity’s potential by using metal, heat, and magnetic fields to produce energy.Image: Chelsea Turner/MITEnergy, Magnets, Materials Science and Engineering, Physics, Research, Research Laboratory of Electronics, School of Science, School of Engineering, Electrical Engineering & Computer Science (eecs)TESS takes initial test imagehttp://news.mit.edu/2018/nasa-tess-takes-initial-test-image-0518
Exoplanet-seeking satellite developed by MIT swings by moon toward final orbit.
Fri, 18 May 2018 12:00:01 -0400School of Sciencehttp://news.mit.edu/2018/nasa-tess-takes-initial-test-image-0518<p><em>The following is adapted from a press release issued today by MIT and NASA's Goddard Space Flight Center.</em></p>
<p>NASA’s next planet hunter, the Transiting Exoplanet Survey Satellite (TESS), is one step closer to searching for new worlds after successfully completing a lunar flyby on May 17. The spacecraft passed about 5,000 miles from the moon, which provided a gravity assist that helped TESS sail toward its final working orbit.&nbsp;</p>
<p>As part of camera commissioning, the science team snapped a two-second test exposure using one of the four TESS cameras. The image, centered on the southern constellation Centaurus, reveals more than 200,000 stars. The edge of the Coalsack Nebula is in the right upper corner and the bright star Beta Centauri is visible at the lower left edge. TESS is expected to cover more than 400 times as much sky as shown in this image with its four cameras during its initial two-year search for exoplanets. A science-quality image, also referred to as a “first light” image, is expected to be released next month in June.&nbsp;&nbsp;</p>
<p>TESS will undergo one final thruster burn on May 30 to enter its science orbit around Earth. This highly elliptical orbit will maximize the amount of sky the spacecraft can image, allowing it to continuously monitor large swaths of the sky. TESS is expected to begin science operations in mid-June after reaching this orbit and completing camera calibrations.&nbsp;&nbsp;</p>
<div class="cms-placeholder-content-video"></div>
<p>Launched from Cape Canaveral Air Force Station on April 18, TESS is the next step in NASA’s search for planets outside our solar system, known as exoplanets. The mission will observe nearly the entire sky to monitor nearby, bright stars in search of transits — periodic dips in a star’s brightness caused by a planet passing in front of the star. TESS is expected to find thousands of exoplanets. NASA’s upcoming James Webb Space Telescope, scheduled for launch in 2020, will provide important follow-up observations of some of the most promising TESS-discovered exoplanets, allowing scientists to study their atmospheres.&nbsp;</p>
<p>TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. George Ricker of MIT’s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission. Additional partners include Orbital ATK, NASA’s Ames Research Center, the Harvard-Smithsonian Center for Astrophysics, and the Space Telescope Science Institute. The TESS science instruments were jointly developed by MIT’s Kavli Institute for Astrophysics and Space Research and MIT’s Lincoln Laboratory. More than a dozen universities, research institutes, and observatories worldwide are participants in the mission.</p>
This test image from one of the four cameras aboard the Transiting Exoplanet Survey Satellite (TESS) captures a swath of the southern sky along the plane of our galaxy. More than 200,000 stars are visible. The image, which is centered in the constellation Centaurus, includes dark tendrils from the Coal Sack Nebula and the bright emission nebula Ced 122 (upper right).The bright star at bottom center is Beta Centauri.Image: NASA/MIT/TESSTESS, Astronomy, Astrophysics, Exoplanets, Kavli Institute, Lincoln Laboratory, NASA, National Science Foundation (NSF), Planetary science, Physics, EAPS, Research, Satellites, School of Science, space, Space, astronomy and planetary scienceEight from MIT receive 2018 Fulbright awardshttp://news.mit.edu/2018/eight-from-mit-receive-fulbright-awards-0518
Graduating students and alumni will conduct research abroad in 2018-19 academic year.Fri, 18 May 2018 11:30:01 -0400Julia Mongo | Office of Distinguished Fellowshipshttp://news.mit.edu/2018/eight-from-mit-receive-fulbright-awards-0518<p>Eight MIT students and recent alumni have been named winners of Fulbright U.S. Student Program research awards. An additional student received an award but declined the grant to pursue other opportunities.</p>
<p>Destinations for this year's Fulbright recipients include Germany, Switzerland, and other countries of the European Union; Chile; and Indonesia. Students' research interests range from astronomy, art criticism, architectural history, and biohacking to neuroscience, nuclear policy, and computer science.</p>
<p>Sponsored by the U.S. Department of State, Fulbright aims to build lasting connections between the people of the United States and the people of other countries through international educational exchange. The Fulbright U.S. Student Program is administered at MIT through the Office of Distinguished Fellowships. The eight 2018 MIT Fulbright Students are:</p>
<p><strong>Julia Cha</strong> will graduate this spring with a bachelor of science in brain and cognitive sciences and minors in biology and music. In Göttingen, Germany, Cha will conduct neuroscience research on epigenetic pathways that mediate the relationship between early depression and later dementia. A three-time recipient of the MIT Emerson Fellowship in classical piano, Cha has performed with the Boston Pops Orchestra and at Carnegie Hall. She anticipates continuing her love of music by playing with the Göttingen Chamber Music Society. After completing her Fulbright year, Cha will matriculate at Harvard Medical School with the goal of becoming an academic physician.</p>
<p><strong>Caitlin Fischer</strong> is a senior majoring in physics with a minor in political science. Her research in the European Union will focus on international nuclear policy and the role played by the EU in facilitating nuclear negotiations. For her community engagement component of Fulbright, she will engage in outreach to inform the general public on issues of nuclear security and disarmament in an international context. At MIT, Fischer has served as president of the Society of Physics Students, a student member of the Committee on Undergraduate Programs, and general manager of the MIT community radio station WMBR 88.1FM.</p>
<p><strong>Skanda Koppula '16</strong> is an MIT graduate student who will receive his master of engineering degree this spring. He graduated from MIT with a bachelor of science in electrical engineering and computer science in June 2016, has interned as a research scientist with Google and Yahoo, and is currently working with NVIDIA’s autonomous driving team. In Switzerland, Koppula will be researching with colleagues at ETH Zurich’s Department of Computer Science the design of a custom hardware processor for accelerating speech and language tasks. An avid motorsports engineer and co-founder of the new MIT/Delft Formula SAE driverless racecar team, Koppula hopes to participate with ETH Zurich’s racing team.</p>
<p><strong>Mary Tsang</strong> <strong>MS '17</strong> graduated from MIT in 2017 with a master of science in media arts and sciences, and has traveled the world as a non-binary artist and biohacker focused on strengthening feminist-oriented civil society participation. In Yogyakarta, Indonesia, Tsang will collaborate with the Microbiology Department at Gadjah Mada University and local community partner Lifepatch for citizen initiatives in art, science, and technology. Tsang’s interdisciplinary biohacking project seeks to extend feminist perspectives of care to local bodies of water. They will be developing low-cost yeast biosensors and fungal remediation protocols to enable grassroots investigation of endocrine-disrupting compounds in nearby rivers.&nbsp;</p>
<p><strong>Jessica Varner</strong> is a fourth-year doctoral student in the History, Theory and Criticism program within the MIT School of Architecture and Planning. As a Fulbright Student in Germany, her architectural history research in Karlsruhe and the Baden-Württemberg region will explore how chemically constituted building materials developed from the 1850s to 1920s. Through the Fulbright program, Varner will conduct research at the Karlsruhe Institute of Technology (KIT) Department of&nbsp;Architekturtheorie&nbsp;and at various academic and corporate archives, including those of the German chemical company BASF.&nbsp;</p>
<p><strong>Emily Watlington</strong> will graduate in June with a master of science in architecture studies (SMArchS) from the History, Theory and Criticism program. Watlington is a recipient of the German-American Fulbright Commission’s Young Professional Journalists award. As an art critic, historian, and journalist in Berlin, she will research the institutions that have shaped contemporary German art criticism and write for German art publications. Watlington is also eager to attend lectures and exhibition openings in Berlin’s vibrant arts scene, and to host a lecture series for the general public on issues surrounding art criticism.</p>
<p><strong>Luke Weisenbach</strong> is a senior majoring in physics who is headed to Germany to conduct astronomy research. At Heidelberg University’s Department of Physics and Astronomy, he will work with Professor Joachim Wambsganss, who has collaborated closely with Weisenbach’s mentor at MIT, Professor Emeritus Paul Schechter. Weisenbach’s research will focus on the effects of gravitational microlensing, with the goal of learning more about how matter distributions within galaxies make quasars twinkle. He also looks forward to participating in Heidelberg’s astronomy public outreach programs. After completing his Fulbright, Weisenbach plans on pursuing a PhD in astronomy and continuing on to academia or research.</p>
<p><strong>Andrew Xia '17</strong> earned a bachelor of science in electrical engineering and computer science and mathematics from MIT in June 2017, and will complete his master of engineering degree in computer science in December. Xia is a recipient of the Fulbright Chile Science Initiative award. In Santiago, he will apply his computer science skills to modeling and preventing fare evasion for the city’s public transportation bus system. Xia will work with faculty from the industrial engineering and mathematical engineering departments at the Universidad de Chile. He hopes to explore Chile’s natural surroundings by biking and hiking in the Andes and engaging in photojournalism.</p>
The eight 2018 MIT Fulbright Students are: (top, l-r) Emily Watlington, Caitlin Fischer, Luke Weisenbach, Julia Cha; (bottom, l-r) Jessica Varner, Andrew Xia, Skanda Koppula, Mary Tsang.Photos courtesy of the students.Awards, honors and fellowships, Students, Undergraduate, graduate, Graduate, postdoctoral, Global, Alumni/ae, Physics, Political science, Mathematics, Biology, Music and theater arts, Brain and cognitive sciences, Media Lab, School of Science, School of Engineering, School of Architecture and Planning, School of Humanities Arts and Social Sciences, International initiatives, Electrical Engineering & Computer Science (eecs)Jeff Gore: A physicist exploring population dynamics of microbeshttp://news.mit.edu/2018/faculty-profile-jeff-gore-0515
MIT professor sees many “big, deep questions in biology” that benefit from study by both physicists and life scientists.Mon, 14 May 2018 23:59:59 -0400Anne Trafton | MIT News Officehttp://news.mit.edu/2018/faculty-profile-jeff-gore-0515<p>It’s a pretty good bet that among MIT’s physics faculty, Jeff Gore is the only one with test tubes of yeast growing in his lab.</p>
<p>Gore, a biophysicist who studies population dynamics, uses yeast and other microbes to explore the fundamental rules that govern phenomena such as population collapse. His microbial communities offer a window into principles that also influence larger-scale populations that are much more difficult to study.</p>
<p>“Microbes are a wonderful experimentally tractable model system to try to ask the kinds of questions we’re interested in, regarding all these phenomena that are also at play in fisheries, or in zebra populations, which are very difficult to approach experimentally,” says Gore, who recently earned tenure in MIT’s Department of Physics.</p>
<p>Since joining MIT’s faculty in 2010, Gore has explored the roles of “cheaters” and “cooperators” in microbial communities, as well as perturbations that can nudge a stable population toward a tipping point that leads to collapse. The rapid timescale of microbial growth allows Gore and his students to conduct an experiment in just a few days, test their predictions, revise their models based on the experimental results, and then launch new experiments.</p>
<p>“Going back and forth between experiment and modeling is a key part of how I like to do science, and it’s really only feasible, given the timescales, in these experimentally tractable organisms with short generation times,” he says.</p>
<p><strong>A physical approach to biology</strong></p>
<p>Gore, who grew up on a Christmas tree farm in Corvallis, Oregon, first visited MIT as a high school senior and immediately felt at home.</p>
<p>“I was staying with an older graduate from my high school at one of the fraternities across the river,” he recalls. “I played ping pong with different members of the fraternity for hours, and chatted with each of them about what they were doing, what they were excited about. It definitely felt like a place that I was going to appreciate.”</p>
<p>Gore began his undergraduate career as a physics major but gradually added more majors until he ended up with four concentrations, in physics, mathematics, economics, and electrical engineering.</p>
<p>After graduating from MIT, Gore went to the University of California at Berkeley, where he began studying electron transport in carbon nanotubes. However, his PhD advisor left Berkeley soon after that, so he switched to a biophysics lab, where he worked on building new kinds of microscopes to look at and manipulate individual biological molecules, such as DNA.&nbsp;&nbsp;</p>
<p>He found that he enjoyed applying tools and strategies from physics to try to discover patterns that underlie biological phenomena.</p>
<p>“I think many physicists, probably myself included, when we first learn biology there are a lot of things to memorize, and we tend not to be very good at memorizing things, so we decide we don’t like it,” Gore says. “But over time I realized that there are a bunch of big, deep questions in biology where the approach of a physicist is complementary to the approach taken by a molecular or cell biologist.”</p>
<p>He says that another appealing aspect of biophysics is that it offers the opportunity to run experiments that can be contained on a lab bench, as opposed to the huge particle colliders that are required to answer many of the fundamental questions remaining in traditional physics.</p>
<p>“I like experiments, and I wanted to do experiments that could be put on a bench, where you could really have the lead in your own project,” he says. “You may not be able to find out the origin of dark matter, but you have real control over your own experiment.”</p>
<p><strong>Population predictions</strong></p>
<p>After finishing his PhD, Gore returned to MIT as a Pappalardo Fellow in the Department of Physics, where he began studying population dynamics of microbes. Using game theory, a mathematical approach traditionally used by economists to predict individuals’ behavior in certain situations, he set out to explore cooperative behavior, which benefits other members of a species at a cost to the individual.</p>
<p>Working with yeast populations in which some members cooperate, by producing an excess of food, and others cheat, by gorging themselves on the food produced by others, Gore found that if an individual benefits even slightly by cooperating, it can survive even when surrounded by individuals that don’t cooperate. This helps to explain the perpetuation of cooperative behavior, which had puzzled biologists because if only the fittest individuals survive, genes for a behavior that benefits other members of the population more than the cooperating individual should die out.</p>
<p>As a faculty member, Gore has expanded his research to include analysis of the conditions that can lead to population collapse. In 2012, he showed that he could measure a population’s risk of collapse by monitoring how quickly it recovers from small disturbances such as food shortages or overcrowding. Later, he found that monitoring variations in population density in neighboring regions — a measure that is easier to obtain — can also be used to predict risk of collapse.</p>
<p>Since Gore joined MIT’s faculty, the physics department has increased its focus on the field of biophysics, hiring three more specialists in that area. That core group, along with several other biophysicists in the department, launched the Physics of Living Systems group about three years ago.</p>
<p>“We’re working to develop a critical mass of faculty who are taking this physics approach to understanding biology, which is different and hopefully complementary to the approach taken by other departments,” Gore says. “There really are a distinct set of approaches to biology in different departments, which is great because the different approaches give different insights.”</p>
Jeff GoreImage: Jared CharneyFaculty, Physics, School of Science, Profile, Biology, Evolution, Microbes, Alumni/aeUnderstanding the proton&#039;s weak sidehttp://news.mit.edu/2018/understanding-proton-weak-side-qweak-experiment-0510
Research from the Qweak experiment provides a precision measurement of the proton’s weak charge.
narrows the search for new physics.
Thu, 10 May 2018 15:55:01 -0400Scott Morley | Laboratory for Nuclear Sciencehttp://news.mit.edu/2018/understanding-proton-weak-side-qweak-experiment-0510<p>A new result from the Qweak experiment at the U.S. Department of Energy’s <a href="https://www.jlab.org/" target="_blank">Thomas Jefferson National Accelerator Facility</a> provides a precision test of the weak force, one of four fundamental forces in nature. This result, <a href="https://www.nature.com/articles/s41586-018-0096-0" target="_blank">published recently in </a><em><a href="https://www.nature.com/articles/s41586-018-0096-0" target="_blank">Nature</a>,</em> also constrains possibilities for new particles and forces beyond our present knowledge.</p>
<p>The Qweak experiment has set new standards in precision tests of the Standard Model, a highly successful theory of fundamental particles and their interactions. It directly probed the physics only reached at the highest energy particle accelerators. MIT efforts were directed by Stanley Kowalski, a professor of physics and researcher in the Laboratory for Nuclear Science (LNS), who has pioneered parity violation studies over the past four decades starting in 1980, at the <a href="http://web.mit.edu/lns/research/bates.html" target="_blank">MIT-Bates Linear Accelerator Center</a>, a part of LNS. Other MIT contributors to the work included postdocs W. Deconinck, Jean-Francoise Rajotte, and Rupesh Silwal. Fang Gao, a physics graduate student, analyzed Qweak data for her PhD thesis. Several MIT undergraduates also worked on many aspects of this experiment.&nbsp;</p>
<p>While the weak force is difficult to observe directly, its influence can be felt in our everyday world. For example, it initiates the chain of reactions that power the sun and it provides a mechanism for radioactive decays that partially heat the Earth’s core and that also enable doctors to detect disease inside the body without surgery.</p>
<p>Now, the Qweak Collaboration has revealed one of the weak force’s secrets: the precise strength of its grip on the proton. They did this by measuring the proton’s weak charge to high precision, which they probed using high-quality beams available at the Continuous Electron Beam Accelerator Facility, a Department of Energy Office of Science User Facility.</p>
<p>The proton’s weak charge is analogous to its more familiar electric charge, a measure of the influence the proton experiences from the electromagnetic force. These two interactions are closely related in the Standard Model, which describes the electromagnetic and weak forces as two different aspects of a single force that interacts with subatomic particles.</p>
<p>To measure the proton’s weak charge, an intense beam of electrons was directed onto a target containing cold liquid hydrogen, and the electrons scattered from this target were detected in a precise, custom-built measuring apparatus. The key to the Qweak experiment is that the electrons in the beam were highly polarized — prepared prior to acceleration to be mostly “spinning” in one direction, parallel or anti-parallel to the beam direction. With the direction of polarization rapidly reversed in a controlled manner, the experimenters were able to latch onto the weak interaction’s unique property of parity (akin to mirror symmetry) violation, in order to isolate its tiny effects to high precision: a different scattering rate by about 2 parts in 10 million was measured for the two beam polarization states.</p>
<p>The proton’s weak charge was found to be QWp=0.0719±0.0045. This turns out to be in excellent agreement with predictions of the Standard Model, which takes into account all known subatomic particles and the forces that act on them. Because the proton’s weak charge is so precisely predicted in this model, the new Qweak result provides insight into predictions of hitherto unobserved heavy particles, such as those that may be produced by the Large Hadron Collider (LHC) at CERN in Europe or future high-energy particle accelerators.</p>
<p>“This very challenging experimental result is yet another clue in the worldwide search for new physics beyond our current understanding. There is ample evidence the Standard Model of Particle physics provides only an incomplete description of nature’s phenomena, but where the breakthrough will come remains elusive,” says Timothy J. Hallman, associate director for nuclear physics of the U.S. Department of Energy Office of Science. “Experiments like Qweak are pressing ever closer to finding the answer.”</p>
<p>For example, the Qweak result has set limits on the possible existence of leptoquarks, hypothetical particles that can reverse the identities of two broad classes of very different fundamental particles, turning quarks (the building blocks of nuclear matter) into leptons (electrons and their heavier counterparts) and vice versa.</p>
<p>"After more than a decade of careful work, Qweak not only informed the Standard Model, it showed that extreme precision can enable moderate-energy experiments to achieve results on par with the largest accelerators available to science," says Anne Kinney, assistant director for the Mathematical and Physical Sciences Directorate at the National Science Foundation. "Such precision will be important in the hunt for physics beyond the Standard Model, where new particle effects would likely appear as extremely tiny deviations."</p>
<p>“It’s complementary information. So, if they find evidence for new physics in the future at the LHC, we can help identify what it might be, from the limits that we’re setting already in this paper,” says Greg Smith, Jefferson Lab senior staff scientist and Qweak project manager.</p>
<p>Kowalski had management responsibilities for the project, as a co-spokesperson. MIT also made very significant contributions to Qweak in two technical areas. Engineers and technicians at the MIT-Bates Laboratory designed, assembled, and tested the large toroidal magnetic spectrometer, QTOR, which directed the scattered electrons to the detectors. QTOR was magnetically mapped and certified by MIT-Bates personnel. Engineers and technicians also designed and built the Compton Polarimeter magnets and beamline, used to measure the polarization of the electron beam. These efforts at MIT-Bates were directed by LNS principal engineers James Kelsey and Ernest Ihloff. Jason Bessuille, who led the QTOR assembly effort as an engineering student, now works at MIT-Bates as a mechanical engineer.</p>
<p>An experiment such as Qweak is a superb training ground for future scientists and engineers. As such, MIT postdocs and students managed data acquisition efforts and data analysis.</p>
<p>Kowalski says, "Qweak provides a very precise measurement of the weak charge of the proton, probing interesting new physics at the highest energies."</p>
<p>The Qweak Collaboration consists of about 100 scientists and more than 20 institutions. The experiment was funded by the U.S. Department of Energy Office of Science, the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, and the Canadian Foundation for Innovation, with matching and in-kind contributions from a number of the collaborating institutions. The MIT effort was funded by a grant from the U.S. Department of Energy.</p>
In the QTor magnetic spectrometer, a magnet separates high-energy electrons, which are elastically scattered from protons. Photo courtesy of the Laboratory for Nuclear Science.Research, Physics, Particles, Laboratory for Nuclear Science, School of Science, Department of Energy (DoE), National Science Foundation (NSF)Ushering in the next phase of exoplanet discoveryhttp://news.mit.edu/2018/ushering-in-next-phase-of-exoplanet-discovery-sara-seager-0503
Professor Sara Seager previews a new era of discovery as a leader of the TESS mission, which is expected to find some 20,000 extrasolar planets. Thu, 03 May 2018 17:10:01 -0400Lauren Hinkel | Oceans at MIThttp://news.mit.edu/2018/ushering-in-next-phase-of-exoplanet-discovery-sara-seager-0503<p>Ever since scientists discovered the first planet outside of our solar system, 51 Pegasi b, the astronomical field of exoplanets has exploded, thanks in large part to the Kepler Space Telescope. Now, with the successful launch of the Transiting Exoplanet Survey Satellite (<a href="http://tess.mit.edu/" target="_blank">TESS</a>), Professor <a href="http://paocweb.mit.edu/people/seager" target="_blank">Sara Seager</a> sees a revolution not only in the amount of new planetary data to analyze, but also in the potential for new avenues of scientific discovery.</p>
<p>“TESS is going to essentially provide the catalog of all of the best planets for following up, for observing their atmospheres and learning more about them,” Seager says. “But it would be impossible to really describe all the different things that people are hoping to do with the data.”</p>
<p>For Seager, the goal is to sift through the plethora of incoming TESS data to identify exoplanet candidates. Ultimately, she says she wants to find the best planets to follow up with atmosphere studies for signs that the planet might be suitable for life.</p>
<p>“When I came to MIT 10 years ago, [MIT scientists] were starting to work on TESS, so that was the starting point,” said&nbsp;Seager, the Class of 1941 Professor Chair in MIT’s Department of Earth, Atmospheric and Planetary Sciences with appointments in the departments of Physics and Aeronautics and Astronautics.</p>
<p>Seager is the deputy science director of TESS, an <a href="http://tess.mit.edu/science/" target="_blank">MIT-led NASA Explorer-class mission</a>. Her credentials include pioneering exoplanet characterization, particularly of atmospheres, that form the foundation of the field. Seager is currently hunting for exoplanets with signs of life, and TESS is the next step on that path.</p>
<p>So far, scientists have confirmed 3,717 exoplanets in 2,773 systems. As an all-sky survey, TESS will build on this, observing 85 percent of the sky containing more than 200,000 nearby stars, and researchers expect to identify some 20,000 exoplanets.</p>
<p>“TESS is trying to take everything that people have already done and do it better and do it across the whole sky,” Seager says. While this mission relies on exoplanet hunting techniques developed years ago, the returns on this work should extend far into the future. “TESS is almost the culmination of a couple of decades of hard work, trying to iron out the wrinkles of how to find planets by the transiting method. So, TESS isn’t changing the way we look for planets, more like it’s riding on the wave of success of how we’ve done it already.”</p>
<p>The TESS science leadership team have committed to delivering at least 50 exoplanets with radii less than four times that of Earth’s along with measured masses. As part of the TESS mission, an international effort to further characterize the planet candidates and their host stars down to the list of 50 with measured masses will be ongoing, using the best ground-based telescopes available.</p>
<p>For the best exoplanets for follow up, Seager likens photons reaching the satellite’s cameras to money: the more photons you have, the better. Accordingly, the cameras are optimized for nearby, bright stars. Furthermore, the cameras are calibrated to favor small, red M dwarf stars, around which small planets with a rocky surface are more easily detected than around the larger, yellow sun-size stars. Additionally, researchers tuned the satellite to exoplanets with orbits of less than 13 days, so that two transits are used for discovery.&nbsp;</p>
<div class="cms-placeholder-content-video"></div>
<p>After 60 days of commissioning, TESS will begin science operations and will be transmitting images to Earth monthly, and the data mining begins. The raw data will be sent to the NASA Ames Research Center’s Science Processing Operations Center to be put through the data analysis pipeline, which was based on the Kepler data pipeline. Here, computer scientists will generate calibrated pixels, light curves, and other data products, which will be shared with MIT to evaluate whether a drop in brightness is due to a planet candidate or, as Seager says, a data artifact or binary star. The team will determine the size of these exoplanets and the period of their orbits, for distribution via the TESS object of interest (TOI) list. This information will be made public and archived at the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. In parallel, the MIT group will analyze their data and images as they come down in what they call the “quick-look pipeline” and start flagging objects to follow up.</p>
<p>The TESS Follow-up Observing Program Working Group will further investigate whether the TOIs are planets, by studying the host stars using imaging from ground and space telescopes, reconnaissance spectroscopy and precise Doppler spectroscopy. For some planets, the follow-up team will ultimately be able to measure the planet’s orbital parameters and mass that, together with radius, determines the planet’s density.</p>
<p>Beyond the TESS follow-up program, additional observations will provide data on orbital dynamics, including planet-planet interactions, mutual inclinations, moons, and tides; atmospheric composition and structure can be inferred through the study of transmission and emission spectra, albedo, phase function measurements.</p>
<p>“I think right now if all goes as planned, our only challenge will be — it’s a good thing — [that] we’ll have so much data.” But, she says she is confident that “MIT can do a great job, not only in delivery in the list of final candidates, but also in groundbreaking new science.”</p>
<p>TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Dr. George Ricker of MIT’s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission.&nbsp;Additional partners include Orbital ATK, NASA’s Ames Research Center, the Harvard-Smithsonian Center for Astrophysics and the Space Telescope Science Institute. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.</p>
An artist concept depicts TESS in front of a lava planet orbiting its host star. Image: NASA Goddard Space Flight CenterExoplanets, Astronomy, Astrophysics, Kavli Institute, NASA, Planetary science, Physics, EAPS, Satellites, Aeronautical and astronautical engineering, School of Science, School of Engineering, Lincoln Laboratory, National Science Foundation (NSF), Research, Space, astronomy and planetary science, TESSSeven from MIT named National Defense Science and Engineering Graduate Fellowshttp://news.mit.edu/2018/mit-grad-students-awarded-national-defense-graduate-fellowships-0502
Fellowships last for up to three years, covering full tuition and mandatory fees. Wed, 02 May 2018 16:25:01 -0400Denis Paiste | Materials Research Laboratoryhttp://news.mit.edu/2018/mit-grad-students-awarded-national-defense-graduate-fellowships-0502<p>Seven MIT graduate students have been awarded 2018 National Defense Science and Engineering Graduate (<a href="http://www.ndsegfellowships.org/" rel="noopener" target="_blank">NDSEG</a>) Fellowships. They are among 69 fellows nationwide offered the highly competitive awards.</p>
<p>NDSEG Fellowships last for up to three years, covering full tuition and mandatory fees. Fellows receive a monthly stipend of $3,200 and a yearly medical insurance stipend.</p>
<p>Fellows are selected by the Air Force Office of Scientific Research, the Army Research Office and the Office of Naval Research. This year's NDSEG Fellows are:</p>
<ul>
<li>Eeshan Chetan Bhatt of the MIT/WHOI Joint Program in Oceanography and Applied Ocean Science and Engineering and the Department of Mechanical Engineering, funded by the Office of Naval Research;</li>
<li>Frederick Daso of the necstlab and the Department of Aeronautics and Astronautics, funded by the Office of Naval Research;</li>
<li>Ashley L. Kaiser of the necstlab and the Department of Materials Science and Engineering, funded by the Air Force Office of Scientific Research;</li>
<li>Bharath Kannan of the Engineering Quantum Systems group and the Department of Electrical Engineering and Computer Science, funded by the Office of Naval Research;</li>
<li>Peter Yucheng Lu of the Photonics and Modern Electro-Magnetics Group and the Department of Physics, funded by the Army Research Office;</li>
<li>Molly Parsons of the Laboratory for Computational Biology and Biophysics and the Department of Biological Engineering, funded by the Office of Naval Research; and</li>
<li>Sarah Schwartz of the Fournier Lab and the Department of Biology, funded by the Army Research Office.</li>
</ul>
<p>“My experience as a 2016 Summer Scholar truly launched my career at MIT even before I returned for graduate school, and it allowed me the key opportunity to pursue and publish my research at a fast pace,” says Kaiser, who worked with Postdoc Itai Y. Stein to create&nbsp;<a dir="ltr" href="http://news.mit.edu/2018/getting-heart-carbon-nanotube-clusters-0214" rel="noopener" target="_self">predictable patterns</a>&nbsp;from unpredictable carbon nanotubes. “I'm very honored and excited to receive this fellowship, as it will support my research goals to develop enhanced nanocomposite technology during my PhD.”</p>
<p>“Winning this award was a culmination of two things: my growing passion for structural analysis as a freshman entering MIT, and Professor [Brian] Wardle's willingness to take on a freshman UROP into his lab group,” adds Daso, whose current research focuses on applying novel curing techniques to process thermoplastic composite materials and reducing or eliminating process-driven deformations during the cure cycle for resin impregnated fabrics. “With Professor Wardle's guidance and support, I was able to cultivate my interests in composite research and focus on getting into graduate school. Winning the award in such a competitive year is a testament to the future impact my work will have in the field of composite materials.”</p>
<p>Begun in 1989, NDSEG has awarded nearly 3,600 fellowships to U.S. citizens and nationals who pursue a doctoral degree in one of 15 supported disciplines at a U.S. institution. The NDSEG Fellowship is sponsored by the Air Force Office of Scientific Research, the Army Research Office, and the Office of Naval Research under the Office of the Assistant Secretary of Defense for Research and Engineering.</p>
Seven MIT graduate students are receiving 2018 National Defense Science and Engineering Graduate Fellowships. Top row, left to right: Eeshan Chetan Bhatt, Frederick Daso, Ashley Kaiser, and Bharath Kannan. Bottom row, left to right: Peter Yucheng Lu, Molly Parsons, and Sarah Schwartz.Awards, honors and fellowships, Graduate, postdoctoral, Students, Materials Research Laboratory, School of Engineering, School of Science, Mechanical engineering, Aeronautical and astronautical engineering, Physics, Electrical Engineering & Computer Science (eecs), Biology, Woods Hole, U.S. Armed Forces, Research, Biological engineeringNational Academy of Sciences elects four MIT professors for 2018http://news.mit.edu/2018/national-academy-sciences-elects-four-mit-professors-0501
Finkelstein, Kardar, Wen, and Zhang honored for research achievements.Tue, 01 May 2018 15:30:00 -0400MIT News Officehttp://news.mit.edu/2018/national-academy-sciences-elects-four-mit-professors-0501<p>Four MIT faculty members have been elected to the National Academy of Sciences (NAS) in recognition of their “distinguished and continuing achievements in original research.”</p>
<p>MIT’s four new NAS members are: Amy Finkelstein, the John and Jennie S. MacDonald Professor of Economics; Mehran Kardar, the Francis Friedman Professor of Physics; Xiao-Gang Wen, the Cecil and Ida Green Professor of Physics; and Feng Zhang, the Patricia and James Poitras ’63 Professor in Neuroscience at MIT, associate professor of brain and cognitive sciences and of biological engineering, and member of the McGovern Institute for Brain Research and the Broad Institute</p>
<p>The group was among 84 new members and 21 new foreign associates elected to the NAS. Membership in the NAS is one of the most significant honors given to academic researchers.</p>
<p><strong>Amy Finkelstein</strong></p>
<p>Finkelstein is the co-scientific director of J-PAL North America, the&nbsp;co-director of the Public Economics Program at the National Bureau of Economic Research, a member of the Institute of Medicine and the American Academy of Arts and Sciences, and a fellow of the Econometric Society.&nbsp;</p>
<p>She has received numerous awards and fellowships including the John Bates Clark Medal (2012), the American Society of Health Economists’ ASHEcon Medal (2014), a Presidential Early Career Award for Scientists and Engineers (2009), the American Economic Association’s Elaine Bennett Research Prize (2008) and a Sloan Research Fellowship (2007). She has also received awards for graduate student teaching (2012) and graduate student advising (2010) at MIT.</p>
<p>She is one of the two principal investigators for the Oregon Health Insurance Experiment, a randomized evaluation of the impact of extending Medicaid coverage to low income, uninsured adults.</p>
<p><strong>Mehran Kardar</strong></p>
<p>Kardar obtained a BA from Cambridge University in 1979 and a PhD in physics from MIT in 1983. He was a junior fellow of the Harvard Society of Fellows from 1983 to 1986 before returning to MIT as an assistant professor, and was promoted to full professor in 1996. He has been a visiting professor at a number of institutions including Catholic University in Belgium, Oxford University, the University of California at Santa Barbara, the University of California at Berkeley, and Ecole Normale Superieure in Paris.&nbsp;</p>
<p>His expertise is in statistical physics, and he has lectured extensively on this topic at MIT and in workshops at universities and institutes in France, the U.K., Switzerland, and Finland. He is the author of two books based on these lectures. In 2018 he was recognized by the American Association of Physics Teachers with the John David Jackson Excellence in Graduate Physics Education Award.</p>
<p>Kardar is a member of the founding board of the New England Complex Science Institute and the editorial board of <em>Journal of Statistical Physics</em>, and has helped organize Gordon Conference and KITP workshops. His awards include the Bergmann memorial research award, the A. P. Sloan Fellowship, the Presidential Young Investigator award, the Edgerton award for junior faculty achievements (MIT), and the&nbsp;Guggenheim Fellowship<em>.</em> He is a fellow of the&nbsp;American Physical Society&nbsp;and the&nbsp;American Academy of Arts and Sciences.</p>
<p><strong>Xiao-Gang Wen</strong></p>
<p>Wen received a BS in physics from University of Science and Technology of China in 1982 and a PhD in physics from Princeton University in 1987.</p>
<p>He studied superstring theory under theoretical physicist Edward Witten at Princeton University and later switched his research field to condensed matter physics while working with theoretical physicists Robert Schrieffer, Frank Wilczek, and Anthony Zee in the Institute for Theoretical Physics at the University of California at Santa Barbara (1987–1989). He became a five-year member of the Institute for Advanced Study at Princeton University in 1989 and joined MIT in 1991. Wen is the Cecil and Ida Green professor of Physics at MIT, a Distinguished Moore Scholar at Caltech, and a Distinguished Research Chair at the Perimeter Institute. In 2017 he received the Oliver E. Buckley Condensed Matter Physics Prize of the American Physical Society.</p>
<p>Wen’s main research area is condensed matter theory. His interests include strongly correlated electronic systems, topological order and quantum order, high-temperature superconductors, the origin and unification of elementary particles, and the Quantum Hall Effect and non-Abelian statistics.</p>
<p><strong>Feng Zhang</strong></p>
<p>Zhang is a bioengineer focused on developing tools to better understand nervous system function and disease. His lab applies these novel tools to interrogate gene function and study neuropsychiatric disorders in animal and stem cell models. Since joining MIT and the Broad Institute in January 2011, Zhang has pioneered the development of genome editing tools for use in eukaryotic cells — including human cells — from natural microbial CRISPR systems. He also developed a breakthrough technology called <a href="https://mcgovern.mit.edu/news/videos/optogenetics-a-light-switch-for-neurons/">optogenetics</a> with Karl Deisseroth at Stanford University and Edward Boyden, now of MIT.</p>
<p>Zhang joined MIT and the Broad Institute in 2011 and was awarded tenure in 2016. He received his BA in chemistry and physics from Harvard College and his PhD in chemistry from Stanford University. Zhang’s award include the Perl/UNC Prize in Neuroscience (2012, shared with Karl Deisseroth and Ed Boyden), the National Institutes of Health Director’s Pioneer Award (2012), the National Science Foundation’s Alan T. Waterman Award (2014), the Jacob Heskel Gabbay Award in Biotechnology and Medicine (2014, shared with Jennifer Doudna and Emmanuelle Charpentier), the Society for Neuroscience Young Investigator Award (2014), the Okazaki award, the Canada Gairdner International Award (shared with Doudna and Charpentier along with Philippe Horvath and Rodolphe Barrangou) and the 2016 Tang Prize (shared with Doudna and Charpentier).</p>
<p>Zhang is a founder of Editas Medicine, a genome editing company founded by world leaders in the fields of genome editing, protein engineering, and molecular and structural biology.</p>
MIT’s four new NAS members are (from left): Feng Zhang, Mehran Kardar, Amy Finkelstein, and Xiao-Gang Wen.Faculty, Awards, honors and fellowships, Economics, School of Humanities Arts and Social Sciences, Physics, School of Science, McGovern Institute, Broad Institute, Brain and cognitive sciences, Biological engineering, School of EngineeringMIT Federal Credit Union presents 2018 scholarships, People Helping People Awardhttp://news.mit.edu/2018/mit-federal-credit-union-presents-scholarships-people-helping-people-award-0430
MIT senior Nick Schwartz honored for his service to the community; six high school and college students awarded $1,000 Memorial Scholarships.Mon, 30 Apr 2018 16:40:01 -0400Scott Hanna | MIT Federal Credit Unionhttp://news.mit.edu/2018/mit-federal-credit-union-presents-scholarships-people-helping-people-award-0430<p>Each year, the MIT Federal Credit Union (FCU) presents the People Helping People Award to a credit union member who exemplifies compassion, commitment to helping others, and a sense of social justice within the MIT community. At this year's annual business meeting on April 25, Nick Schwartz, a senior at MIT studying mechanical engineering, was named as the 2018 winner.</p>
<p>“Even after 12 years, I am continuously amazed at the submissions we receive each year. I love learning about the contributions and positive impacts our members have on their communities,” said MIT FCU President and CEO Brian Ducharme. “I am honored to present these students and members of the MIT community with their awards at our annual meeting.”</p>
<p>Schwartz has spent the last four years at MIT dedicating himself to the well-being of the MIT community through all of his actions, from formal endeavors to his day-to-day interactions on campus. Since freshman year, Schwartz has been a volunteer counselor with Camp Kesem at MIT, a student-run organization supporting children touched by a parent’s cancer diagnosis. This year will be Schwartz’s last year as a counselor, but he was recently accepted to be a camp advisor and will work with the national organization to improve Camp Kesem chapters around the country.</p>
<p>In addition to his work with Camp Kesem, Schwartz has mentored others through the Leadership Training Institute and worked with the Practical Education Network in Ghana. He uses his engineering skills to help others as well, working to develop prosthetic devices for use in developing countries through MIT’s D-Lab. Recognized both for his exemplary character and exceptional academics, Schwartz has recently been named a Marshall Scholar and will begin graduate studies at the University College London in the fall and will serve as an ambassador between the United States and United Kingdom.</p>
<p>Given all that he does for the MIT community, it is clear how Schwartz is able to translate his many academic and personal interests into a passion for helping others. Schwartz has pledged to donate his $2,000 award to Camp Kesem – MIT.</p>
<p>In addition to the People Helping People Award, MIT FCU awarded six $1,000 Memorial Scholarships to support members investing in their education. Recipients were selected based on essay content, grades, financial need, and extracurricular and community activities. The 2018 Memorial Scholarship winners are:</p>
<ul>
<li>Dianna Gagnon, of Reading, Massachusetts, who is currently finishing her senior year at Reading Memorial High School and plans to attend Wheaton College this fall;</li>
<li>Jessica Quaye, of Cambridge, Massachusetts, who is currently a sophomore at MIT studying electrical engineering;</li>
<li>Noam Watt, of Lexington, Massachusetts, who is currently finishing his senior year at Lexington High School and is still deciding between Northwestern and University of Connecticut for the fall;</li>
<li>Sloan Kanaski, of Cambridge, Massachusetts, who is currently a sophomore at MIT studying physics;</li>
<li>Talya Klinger, of Cambridge, Massachusetts, who is currently a sophomore at MIT studying physics; and</li>
<li>Haley Clemons, of West Newbury, Massachusetts, who is currently finishing her senior year at Pentucket Regional High School and plans to attend University of Maine Orono this fall.</li>
</ul>
<p>MIT Federal Credit Union was founded as a nonprofit financial institution in 1940 to provide basic financial services to employees at MIT. Today, with assets in excess of $500,000 million, the credit union offers traditional savings and checking accounts as well as lending programs for mortgages, autos, personal and student loans. With locations and ATMs in Cambridge and Lexington, along with mobile and, online banking services, MITFCU serves the greater MIT-Kendall Square communities which includes employees of Novartis (Cambridge), Lincoln Laboratory, Draper, Whitehead Institute, The Broad Institute, Phillips, and Forsyth. MITFCU also serves MIT students (graduate and undergraduate) and alumni. MITFCU is a member-owned, cooperative financial institution whose primary mission is to provide quality financial services that meet the needs of its members while ensuring the financial well-being of the organization.</p>
Left to right: 2018 Memorial Scholarship winners Dianna Gagnon, Noam Watt, Sloan Kanaski; MIT FCU President and CEO Brian Ducharme; Memorial Scholarship winners Jessica Quaye and Talya Klinger.Photo: MIT Federal Credit UnionAwards, honors and fellowships, Credit union, Community, Students, Mechanical engineering, Physics, D-Lab, Electrical Engineering & Computer Science (eecs), School of Science, Special events and guest speakers, School of EngineeringCelebrating great mentorship for graduate studentshttp://news.mit.edu/2018/celebrating-great-mentorship-for-graduate-students-0424
MIT’s Committed to Caring Award selects third slate of dedicated professors.Tue, 24 Apr 2018 13:40:01 -0400Office of Graduate Educationhttp://news.mit.edu/2018/celebrating-great-mentorship-for-graduate-students-0424<p>“When we talk about our experiences as graduate students at MIT, my colleagues and I tend to use words like ‘challenging,’ ‘rewarding,’ ‘inspiring,’ or ‘stressful’,” says Courtney Lesoon, the 2017-2018 Graduate Community Fellow for the Committed to Caring Program and a PhD student in the History, Theory and Criticism Section of the Department of Architecture. “Usually our discussions center around our research interests, new findings in our field, or upcoming deadlines.”</p>
<p>The conversation about challenges and stresses at MIT, though, is arguably shifting. A number of new programs have been initiated across campus that prioritize emotional and mental health not just as supplementary to the lives of students, but as integral to them. Such programs include MindHandHeart, the campus coalition to support community wellness; work of the Institute Community and Equity Office (ICEO); Active Minds, the student-led initiative for better health and wellness; and Committed to Caring (C2C), which honors caring faculty on campus.</p>
<p>In recent years, a growing <a href="https://www.nature.com/articles/nbt.4089" target="_blank">body of research</a> has highlighted the importance of advising and mentorship to graduate students’ academic experience and well-being. The Committed to Caring program recognizes that in graduate school, advisors and mentors set the tone for student experiences, and positive faculty support has the ability to shape student research and lives for the better. C2C honors professors who build inclusive cultures in their labs and classrooms, who support their students’ mental and emotional health, and who actively support their students’ scholarly pursuits. Selected faculty members are showcased via a broad campus poster campaign, individual profiles housed on the Office of Graduate Education website, and <em>MIT News </em>articles.</p>
<p><strong>A celebration of caring</strong></p>
<p>On April 11, a celebration was held to honor all past Committed to Caring awardees, as well as the 28 new awardees listed below. Profiles for the first two slates of C2C awardees may be found on the Committed to Caring website.</p>
<p>The event, held in the Samberg Conference Center, was hosted by Vice Chancellor Ian Waitz and included remarks by Provost Martin Schmidt and Senior Associate Dean for Graduate Education Blanche Staton. Formal recognition of these new awardees will be ongoing throughout the 2018-2019 academic year, as pairs of posters and profiles are released each month.</p>
<p>The following faculty members are the 2017-2018 recipients of the Committed to Caring Award:</p>
<p>Emilio Baglietto, Department of Nuclear Science and Engineering</p>
<p>Cullen Buie, Department of Mechanical Engineering</p>
<p>Paola Cappellaro, Department of Nuclear Science and Engineering</p>
<p>Gabriella Carolini , Department of Urban Studies and Planning</p>
<p>Anna Frebel, Department of Physics</p>
<p>Paula Hammond, Department of Chemical Engineering</p>
<p>Wesley Harris, Department of Aeronautics and Astronautics</p>
<p>Erin Kelly, Sloan School of Management</p>
<p>Tom Kochan, Sloan School of Management</p>
<p>Ju Li, Department of Materials Science and Engineering</p>
<p>John Lienhard, Department of Mechanical Engineering</p>
<p>Eytan Modiano, Department of Aeronautics and Astronautics</p>
<p>Susan Murcott, Department of Urban Studies and Planning</p>
<p>Bradley Olsen, Department of Chemical Engineering</p>
<p>Agustin Rayo, Department of Linguistics and Philosophy</p>
<p>Rebecca Saxe, Department of Brain and Cognitive Sciences</p>
<p>Warren Seering, Department of Mechanical Engineering</p>
<p>Julie Shah, Department of Aeronautics and Astronautics</p>
<p>Matthew Shoulders, Department of Chemistry</p>
<p>Hadley Sikes, Department of Chemical Engineering</p>
<p>Justin Steil, Department of Urban Studies and Planning</p>
<p>David Trumper, Department of Mechanical Engineering</p>
<p>Lily Tsai, Department of Political Science</p>
<p>Harry Tuller, Department of Materials Science and Engineering</p>
<p>Evelyn Wang, Department of Mechanical Engineering</p>
<p>Kamal Youcef-Toumi, Department of Mechanical Engineering</p>
<p>Jinhua Zhao, Department of Urban Studies and Planning</p>
<p>Ezra Zuckerman, Sloan School of Management</p>
<p><strong>Student centered, student driven</strong></p>
<p>Graduate students from across MIT’s campus are invited by the Office of Graduate Education (OGE) to nominate professors whom they believe to be outstanding mentors for the Committed to Caring Award. The nominations are then parsed by a selected committee composed primarily of graduate students, with additional representation by staff and faculty in the form of a prior recipient.</p>
<p>Selection criteria for C2C include the scope and reach of advisor impact on the experience of graduate students, excellence in scholarship, and demonstrated commitment to diversity and inclusion. By recognizing the human element of graduate education, C2C aims to encourage good advising and mentorship across MIT’s campus. The C2C Program was conceived in 2014 by Monica Orta, then-OGE assitant director for diverisity initiatives, and implemented by Orta and OGE Communications officer Heather Konar.</p>
<p>The work is driven each year by one graduate student who serves as the C2C Graduate Community Fellow and works closely with Konar. This year’s selection committee included Assistant Dean for Graduate Education Suraiya Baluch (chair), Professor Amy Glasmeier (previous C2C honoree), and graduate students Courtney Lesoon (2017-18 C2C Graduate Community Fellow), Claire Duvallet, Danielle Olson, and Jennifer Cherone (2016-17 C2C Graduate Community Fellow).</p>
<p><strong>A process of affirmation</strong></p>
<p>The C2C Program contributes to OGE’s mission of making graduate education at MIT “empowering, exciting, holistic, and transformative.” The opening of nominations in 2014 received a strong response, and the number and richness of nominations in subsequent rounds has only grown.</p>
<p>Baluch remarked of the most recent selection round, “It was heartwarming to read the numerous accounts regarding acts of compassion, kindness and generosity of spirit in our community. It speaks to the power and impact acts of caring have that so many students felt compelled to participate in the nominating process. These acts were often simple, every day actions such as regularly inquiring about someone's wellbeing or sharing a meal as well as responding with humanity to life's struggles.”</p>
<p>In 2017, the OGE received 114 nominations for 72 faculty members across campus. Committee members expressed being deeply moved by the thoughtful, sincere, and touching nominations that were submitted. Blanche Staton, senior associate dean for graduate education, says “I am grateful to our students for recognizing the caring and positive spirit and the contributions of our faculty, and I join them in applauding the professors who, by their example, show us all what it truly means to ‘advance a caring and respectful community’."</p>
<p><strong>Guideposts for strong mentoring</strong></p>
<p>As the committee reviewed this past year’s nominations, a number of striking themes emerged. Supported by numerous personal quotes, fellow Courtney Lesoon and the C2C team developed a list of “Mentoring Guideposts” that reflect acts of mentorship that seem to be the most meaningful and formative.</p>
<p>MIT graduate students were moved to nominate mentors who:</p>
<ul>
<li>actively show empathy for students’ personal experiences;</li>
<li>advocate for students both academically and personally;</li>
<li>validate students by demonstrating interest in their research and ideas;</li>
<li>encourage and support students in developing a healthy work/life balance;</li>
<li>have courageous conversations about issues that impact students outside of MIT, such as political developments, personal loss, or housing needs;</li>
<li>initiate contact with students, check in consistently, and provide extra support as needed;</li>
<li>provide a channel for students to express their difficulties, including the means to do so anonymously;</li>
<li>foster a friendly and inclusive work environment;</li>
<li>emphasize learning, development, and practice over achievement and goals; and</li>
<li>advise informally, teaching students about the system of academia, the importance of networking, and professional development skills.</li>
</ul>
<p>The C2C team is exploring ideas to disseminate the guideposts widely across campus.</p>
Honorees Ahmed Ghoniem (left) and Wesley Harris enjoy the Committed to Caring celebration on April 11.Photo: Joseph LeeAwards, honors and fellowships, Faculty, Graduate, postdoctoral, Nuclear science and engineering, Mechanical engineering, Urban studies and planning, Physics, Chemical engineering, Aeronautical and astronautical engineering, DMSE, Linguistics, Philosophy, Brain and cognitive sciences, Chemistry, Political science, School of Science, School of Engineering, School of Humanities Arts and Social Sciences, School of Architecture and Planning, Sloan School of Management, Vice Chancellor, Education, teaching, academicsDeriving a theory of defectshttp://news.mit.edu/2018/deriving-theory-of-defects-mingda-li-0419
Mingda Li seeks to harness atomic irregularities in materials for improved energy applications.Thu, 19 Apr 2018 15:45:01 -0400Leda Zimmerman | Department of Nuclear Science and Engineeringhttp://news.mit.edu/2018/deriving-theory-of-defects-mingda-li-0419<p>“I only recently decided on the area to which I would dedicate decades of my life,” confides&nbsp;<a href="http://web.mit.edu/nse/people/faculty/mli.html" target="_blank">Mingda Li</a>&nbsp;PhD ’15, who has just been appointed assistant professor in the Department of Nuclear Science and Engineering. “I could not commit until I became mentally mature enough to make real contributions.”</p>
<p>The area Li today calls his own, and where he is indeed generating significant advances, lies at the intersection of quantum physics and engineering. His research characterizing complex defects in materials has the potential to break through efficiency barriers in a wide range of energy applications.</p>
<p>In five papers published in 2017, including two in the&nbsp;<em>Nano Letters</em>, Li and his co-authors described a new approach to understanding a common type of material defect called a crystal dislocation, proposing a theoretical new particle named a “dislon” to help capture the mechanism underlying dislocation.</p>
<p>“These defects show up everywhere — in metals, semiconductors, insulators,” says Li. Caused by stress, they emerge naturally in crystals, disrupting the precise lattice arrangement of atoms, and affecting a wide range of properties in materials, including electrical and thermal behavior.</p>
<p>Previous attempts had failed to precisely delineate the mechanism for these dislocations. Li, conducting postdoctoral research with advisors Gang Chen, the Soderberg Professor and head of the Department of Mechanical Engineering, and the late Institute Professor Emerita Mildred S. Dresselhaus, drew on quantum field theory to contrive a mathematical approach for explaining dislocations. His quantum dislocation framework, based on hundreds of pages of derivations, can determine how dislocations change materials.</p>
<p>“We came up with one equation to compute any properties caused by dislocation — electrical, optical, magnetic, thermal, even superconducting,” says Li.</p>
<p>With his innovative approach, Li believes it will be possible to transform dislocations from mere defects into a new material tuning dimension. “We will be able to tailor them to improve the performance of many kinds of materials, including those used in thermoelectric technologies, nuclear reactor claddings, solar panels, and semiconductor microelectronics,” says Li.</p>
<p><strong>Uncertain beginnings</strong></p>
<p>This accomplishment, which has vaulted Li to prominence in the field, comes after a long journey during which Li sometimes struggled to find his bearings. Growing up in Tsingtao, China, Li felt at an early age “a great passion for mathematics,” and for computer science in particular. “I adored Bill Gates, and with access to a personal computer at school, taught myself programming,” he says.</p>
<p>He avidly read comics, especially the popular Doraemon manga series, named for a robot cat who travels back in time to protect a boy. “The boy was really unlucky, criticized by tyrants,” recalls Li. “I wished I had my own robot, but then I finally decided to become the Doraemon.”</p>
<p>With his move to a boarding high school in Beijing, Li began to explore disciplines with great intensity. He entertained a life in mathematics, but gave that up before college. “I needed true genius and intuition, and realized I had that only 5 percent of the time.” So he turned to physics and engineering. “I had an eagerness to learn and create something new, to make me feel excited and happy,” he says.</p>
<p>At Tsinghua University, he took up high energy and laser physics, but then turned to nuclear science, whose promise of unlimited energy intrigued him. After encountering MIT transfer students, Li decided to pursue doctoral studies in nuclear science and engineering in the U.S. with “the world’s leading experts” at MIT.</p>
<p><strong>Finding the right path</strong></p>
<p>At NSE, Li initially worked on questions of X-ray scattering. “I was interested in particle dynamics at a nanometer scale, trying to understand how there’s something beyond material structure that can influence properties.”</p>
<p>After a project in high end electron microscopy fell through, Li felt stuck. “I didn’t have a good thesis topic, and had no idea what to do next,” he recalls.</p>
<p>In search of direction, Li approached his advisor, Ju Li, the Battelle Energy Alliance Professor of Nuclear Science and Engineering, for advice. “He just told me to do great science,” recalls Li. “This made me feel both anxious and immensely free, because I needed to design an interesting project from the ground up, finding suitable collaborators, and resources, which I finally did.”</p>
<p>For his dissertation, Li began studying topological materials, “semiconductors that behave weirdly,” using spectroscopic and other methods. “These materials live in a quantum world, and they act very different from traditional materials, especially in terms of electron and thermal transport,” he says. For his postdoctoral research, he “was thinking bigger and crazier,” he says, with studies of topological materials culminating in his pathbreaking dislon framework.</p>
<p>Today, Li is extending this research, working with materials in his own lab to see how defects might improve the performance of technologies society depends on. “People want to build transmission lines without heat loss,” says Li, citing one example. “We need to learn how to tune material properties in the right direction.”</p>
<p>He has a long-term ambition to develop a comparable framework for analyzing amorphous materials like cement. “If we want to build structures that last forever, we need to understand their behaviors better.”</p>
<p>Most of all, he relishes the freedom of his new academic life, and the growing MIT network that sustains his research passions. “I have so many talented colleagues, friends, and students, who talk and get excited together every day,” says Li. “I really treasure this community.”</p>
Assistant professor of nuclear science and engineering Mingda Li relishes the freedom of his new academic life, and the growing MIT network that sustains his research passions.Photo: Lillie Paquette/MIT School of EngineeringFaculty, Profile, Alternative energy, Nuclear power and reactors, Materials Science and Engineering, Physics, Nuclear science and engineering, Mechanical engineering, School of Engineering, EnergyOr Hen receives 2018 Guido Altarelli Awardhttp://news.mit.edu/2018/or-hen-receives-guido-altarelli-award-0418
Assistant professor of physics and Laboratory for Nuclear Science researcher recognized for major contributions to high energy and nuclear physics.Wed, 18 Apr 2018 16:00:01 -0400Scott Morley | Laboratory for Nuclear Sciencehttp://news.mit.edu/2018/or-hen-receives-guido-altarelli-award-0418<p>Or Hen, MIT assistant professor of physics and a researcher in the Laboratory for Nuclear Science, is the recipient of the 2018 Guido Altarelli Award. The award honors the memory of the late Italian physicist Guido Altarelli, a pioneer of the unraveling of the strong interaction and the structure of hadrons, an outstanding communicator of particle physics, and a mentor and strong supporter of junior scientists.</p>
<p>The citation of the award is “for his role in uncovering a striking relation of the nuclear EMC effect and the strength of nucleon-nucleon correlations, with implications for the constraint of the down and up quark distribution ratio at large x.” Hen received the award at the 26th International Workshop on Deep-Inelastic Scattering, in Kobe, Japan, where he also presented a plenary talk on this work.</p>
<p>The EMC effect is an observation that the proton and neutron's building blocks, called quarks, are distributed differently in heavy versus light nuclei. Put into simple words, it implies that the internal structure of protons and neutrons, commonly called nucleons, is modified when bound in an atomic nucleus. The first observation of this effect was very surprising and immediately drew vast attention from theorists trying to explain it and experimentalist measuring it in various nuclei.</p>
<p>Thirty-five years later, with over 1,000 papers written in an attempt to explain it, we still lack an accepted explanation for the origin of the EMC effect. “It’s challenging because of the very different energy scales involved in the problem” says Hen. “The average nuclear binding energy is so small compared to the energy due to the interactions between quarks, that it doesn’t make any sense that the quarks will be significantly impacted by the nuclear environment.” Hen explains, “It’s like the fact that it’s a windy day will affect the way we move around the room, when all the windows are closed.”</p>
<p>To come up with a plausible explanation to this effect, Hen and collaborators took a different view on the problem. Instead of considering ‘static’ effects, that would modify all nucleons all the time, they considered temporal fluctuation effects, that significantly modify some of the nucleons for part of the time. These temporal fluctuations are pairs of nucleons that occasionally get close to each other and experience much stronger interactions than the average. They are referred to as “short-range correlations” and are the primary focus of the research program of Hen and his group at MIT.</p>
<p>By analyzing various data sets, Hen and his collaborators were able to show that the average amount by which a nucleon is modified in a nucleus is linearly correlated with the number of such short-range correlated nucleon pairs. “Prof. Hen’s work provides a vital new direction for future work by both theorists and experimentalists.” says Professor Gerald Miller from the University of Washington. “It also allowed gaining new insight to the structure of the free neutron which has vast implications to our understanding of the strong nuclear interaction.”</p>
<p>The Hen group is also leading the next generation of experiments at the Department of Energy's Thomas Jefferson National Accelerator Facility located in Virginia, where they will test their theory by studying how the internal structure of correlated nucleon pairs is modified as a function of their relative distance. The experiments rely on state-of-the-art fast neutron detectors and laser calibration systems being developed by Hen’s group at MIT’s Laboratory for Nuclear Science and the BATES engineering research center.</p>
<p>Hen received his undergraduate degree in physics and computer engineering from the Hebrew University and earned his PhD in experimental physics at Tel-Aviv University. Prior to joining the MIT physics faculty in 2017, Hen was an MIT Pappalardo Fellow in Physics. Hen has previously received various prizes and fellowships for his work including: the Bose Fellowship, the Fermi Lab Intensity-Frontier fellowship, the Rothschild Fellowship, and the A. Pazi and J. Eisenberg research awards.</p>
<p>This work is supported by the Office of Science at the U.S. Department of Energy.</p>
Or Hen receives the Guido Altarelli Award.Photo courtesy of Or Hen.Faculty, Awards, honors and fellowships, Physics, Laboratory for Nuclear Science, Nuclear science and engineering, School of ScienceEight from MIT elected to American Academy of Arts and Sciences for 2018http://news.mit.edu/2018/mit-faculty-elected-american-academy-arts-and-sciences-0418
Prestigious honor society announces 213 new members this year.Wed, 18 Apr 2018 10:30:00 -0400MIT News Officehttp://news.mit.edu/2018/mit-faculty-elected-american-academy-arts-and-sciences-0418<div class="field field-name-field-article-content field-type-text-long field-label-hidden">
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<p>Eight MIT faculty members are among 213 leaders from academia, business, public affairs, the humanities, and the arts elected to the American Academy of Arts and Sciences, the academy announced today.</p>
<p>One of the nation’s most prestigious honorary societies, the academy is also a leading center for independent policy research. Members contribute to academy publications, as well as studies of science and technology policy, energy and global security, social policy and American institutions, the humanities and culture, and education.</p>
<p>Those elected from MIT this year are:</p>
<ul>
<li>Alexei Borodin, professor of mathematics;</li>
<li>Gang Chen, the Carl Richard Soderberg Professor of Power Engineering and head of the Department of Mechanical Engineering;</li>
<li>Larry D. Guth; professor of mathematics;</li>
<li>Parag A. Pathak, the Jane Berkowitz Carlton and Dennis William Carlton Professor of Microeconomics;</li>
<li>Nancy L. Rose, the Charles P. Kindleberger Professor of Applied Economics and head of the Department of Economics;</li>
<li>Leigh H. Royden, professor of earth, atmostpheric, and planetary sciences;</li>
<li>Sara Seager, the Class of 1941 Professor in the Department of Earth, Atmospheric and Planetary Sciences with a joint appointment in the Department of Physics; and</li>
<li>Feng Zhang, the James and Patricia Poitras Professor of Neuroscience within the departments of Brain and Cognitive Sciences and Biological Engineering, and an <span class="st">investigator</span> at the <span class="st">McGovern Institute for Brain Research at MIT. </span></li>
</ul>
<p>“This class of 2018 is a testament to the academy’s ability to both uphold our 238-year commitment to honor exceptional individuals and to recognize new expertise,” said Nancy C. Andrews, chair of the board of the American Academy.</p>
<p>“Membership in the academy is not only an honor, but also an opportunity and a responsibility,” added Jonathan Fanton, president of the American Academy. “Members can be inspired and engaged by connecting with one another and through academy projects dedicated to the common good. The intellect, creativity, and commitment of the 2018 class will enrich the work of the academy and the world in which we live.”</p>
<p>The new class will be inducted at a ceremony in October in Cambridge, Massachusetts.</p>
<p>Since its founding in 1780, the academy has elected leading “thinkers and doers” from each generation, including George Washington and Benjamin Franklin in the 18th century, Maria Mitchell and Daniel Webster in the 19th century, and Toni Morrison and Albert Einstein in the 20th century. The current membership includes more than 200 Nobel laureates and 100 Pulitzer Prize winners.</p>
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MIT Killian CourtPhoto: Jake BelcherFaculty, Awards, honors and fellowships, Mathematics, Mechanical engineering, Economics, EAPS, Physics, Brain and cognitive sciences, Biological engineering, Broad Institute, McGovern Institute, School of Engineering, School of Science, School of Humanities Arts and Social SciencesTESS readies for takeoffhttp://news.mit.edu/2018/tess-readies-takeoff-discover-exoplanets-0412
Satellite developed by MIT aims to discover thousands of nearby exoplanets, including at least 50 Earth-sized ones.Thu, 12 Apr 2018 10:30:00 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/tess-readies-takeoff-discover-exoplanets-0412<p>There are potentially thousands of planets that lie just outside our solar system — galactic neighbors that could be rocky worlds or more tenuous collections of gas and dust. Where are these closest exoplanets located? And which of them might we be able to probe for clues to their composition and even habitability? The Transiting Exoplanet Survey Satellite (TESS) will be the first to seek out these nearby worlds.</p>
<p>The NASA-funded spacecraft, not much larger than a refrigerator, carries four cameras that were conceived, designed, and built at MIT, with one wide-eyed vision: to survey the nearest, brightest stars in the sky for signs of passing planets.</p>
<p>Now, more than a decade since MIT scientists first proposed the mission, TESS is about to get off the ground. The spacecraft is scheduled to launch on a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station in Florida, no earlier than April 16, at 6:32 p.m. EDT.</p>
<p><img alt="" src="/sites/mit.edu.newsoffice/files/TESS.gif" /></p>
<p><span style="font-size:10px;"><em>The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest stars in the sky. In a two-year survey of the solar neighborhood, TESS will monitor more than 200,000 stars for temporary drops in brightness caused by planetary transits. This first-ever space borne all-sky transit survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances. No ground-based survey can achieve this feat. (NASA's Goddard Space Flight Center/CI Lab)</em></span></p>
<p>TESS will spend two years scanning nearly the entire sky — a field of view that can encompass more than 20 million stars. Scientists expect that thousands of these stars will host transiting planets, which they hope to detect through images taken with TESS’s cameras.</p>
<p>Amid this extrasolar bounty, the TESS science team at MIT aims to measure the masses of at least 50 small planets whose radii are less than four times that of Earth. Many of TESS’s planets should be close enough to our own that, once they are identified by TESS, scientists can zoom in on them using other telescopes, to detect atmospheres, characterize atmospheric conditions, and even look for signs of habitability.</p>
<p>“TESS is kind of like a scout,” says Natalia Guerrero, deputy manager of TESS Objects of Interest, an MIT-led effort that will catalog objects captured in TESS data that may be potential exoplanets.</p>
<p>“We’re on this scenic tour of the whole sky, and in some ways we have no idea what we will see,” Guerrero says. “It’s like we’re making a treasure map: Here are all these cool things. Now, go after them.”</p>
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<p><strong>A seed, planted in space</strong></p>
<p>TESS’s origins arose from an even smaller satellite that was designed and built by MIT and launched into space by NASA on Oct. 9, 2000. The High Energy Transient Explorer 2, or HETE-2, orbited Earth for seven years, on a mission to detect and localize gamma-ray bursts — high-energy explosions that emit massive, fleeting bursts of gamma and X-rays.</p>
<p>To detect such extreme, short-lived phenomena, scientists at MIT, led by principal investigator George Ricker, integrated into the satellite a suite of optical and X-ray&nbsp; cameras outfitted with CCDs, or charge-coupled devices, designed to record intensities and positions of light in an electronic format.</p>
<p>“With the advent of CCDs in the 1970s, you had this fantastic device … which made a lot of things easier for astronomers,” says HETE-2 team member Joel Villasenor, who is now also instrument scientist for TESS. “You just sum up all the pixels on a CCD, which gives you the intensity, or magnitude, of light. So CCDs really broke things open for astronomy.”</p>
<p>In 2004, Ricker and the HETE-2 team wondered whether the satellite’s optical cameras could pick out other objects in the sky that had begun to attract the astronomy community: exoplanets. Around this time, fewer than 200 planets&nbsp;outside our&nbsp;solar system had been discovered. A few of these were found with a technique&nbsp;known as the transit method, which involves looking for periodic dips in the light from certain stars, which may signal a planet passing in front of the star.</p>
<p>“We were thinking, was the photometry of HETE-2’s cameras sufficient so that we could point to a part of the sky and detect one of these dips? Needless to say, it didn’t exactly work,” Villasenor recalls. “But that was sort of the seed that started us thinking, maybe we should try to fly CCDs with a camera to try and detect these things.”</p>
<p><strong>A path, cleared</strong></p>
<p>In 2006, Ricker and his team at MIT proposed a small, low cost satellite (HETE-S) to NASA as a Discovery class mission, and later on as a privately funded mission for $20 million. But as the cost of, and interest in, an all-sky exoplanet survey grew, they decided instead to seek NASA funding, at a higher level of $120 million. In 2008, they submitted a proposal for a NASA Small Explorer (SMEX) Class Mission with the new name — TESS.</p>
<p>At this time, the satellite design included six CCD cameras, and the team proposed that the spacecraft fly in a low-Earth orbit, similar to that of HETE-2. Such an orbit, they reasoned, should keep observing efficiency relatively high, as they already had erected data-receiving ground stations for HETE-2 that could also be put to use for TESS.</p>
<p>But they soon realized that a low-Earth orbit would have a negative impact on TESS’s much more sensitive cameras. The spacecraft’s reaction to the Earth’s magnetic field, for example, could lead to significant “spacecraft jitter,” producing noise that hides an exoplanet’s telltale dip in starlight.</p>
<p>NASA bypassed this first proposal, and the team went back to the drawing board, this time emerging with a new plan that hinged on a completely novel orbit. With the help of engineers from Orbital ATK, the Aerospace Corporation, and NASA’s Goddard Space Flight Center, the team identified a never-before-used “lunar-resonant” orbit that would keep the spacecraft extremely stable, while giving it a full-sky view.</p>
<p>Once TESS reaches this orbit, it will slingshot between the Earth and the moon on a highly elliptical path that could keep TESS orbiting for decades, shepherded by the moon’s gravitational pull.</p>
<p>“The moon and the satellite are in a sort of dance,” Villasenor says. “The moon pulls the satellite on one side, and by the time TESS completes one orbit, the moon is on the other side tugging in the opposite direction. The overall effect is the moon’s pull is evened out, and it’s a very stable configuration over many years. Nobody’s done this before, and I suspect other programs will try to use this orbit later on.”</p>
<p>In its current planned trajectory, TESS will swing out toward the moon for less than two weeks, gathering data, then swing back toward the Earth where, on its closest approach, it will transmit the data back to ground stations from 67,000 miles above the surface before swinging back out. Ultimately, this orbit will save TESS a huge amount of fuel, as it won’t need to burn its thrusters on a regular basis to keep on its path.</p>
<p>With this revamped orbit, the TESS team submitted a second proposal in 2010, this time as an Explorer class mission, which NASA approved in 2013. It was around this time that the Kepler Space Telescope ended its original survey for exoplanets. The observatory, which was launched in 2009, stared at one specific patch of the sky for four years, to monitor the light from distant stars for signs of transiting planets.</p>
<p>By 2013, two of Kepler’s four reaction wheels had worn out, preventing the spacecraft from continuing its original survey. At this point, the telescope’s measurements had enabled the discovery of nearly 1,000 confirmed exoplanets. Kepler, designed to study far-off stars, paved the way for TESS, a mission with a much wider view, to scan the nearest stars to Earth.</p>
<p>“Kepler went up, and was this huge success, and researchers said, ‘We can do this kind of science, and there are planets everywhere,” says TESS member Jennifer Burt, an MIT-Kavli postdoc. “And I think that was really the scientific check box that we needed for NASA to say, ‘Okay, TESS makes a lot of sense now.’ It’ll enable not just detecting planets, but finding planets that we can thoroughly characterize after the fact.”</p>
<p><strong>Stripes in the sky</strong></p>
<p>With the selection by NASA, the TESS team set up facilities on campus and in MIT’s Lincoln Laboratory to build and test the spacecraft’s cameras. The engineers designed “deep depletion” CCDs specifically for TESS, meaning that the cameras can detect light over a wide range of wavelengths up to the near infrared. This is important, as many of the nearby stars TESS will monitor are red-dwarfs — small, cool stars that emit less brightly than the sun and in the infrared part of the electromagnetic spectrum.</p>
<p>If scientists can detect periodic dips in the light from such stars, this may signal the presence of planets with significantly tighter orbits than that of Earth. Nevertheless, there is a chance that some of these planets may be within the “habitable zone,” as they would circle much cooler stars, compared with the sun. Since these stars are relatively close by, scientists can do follow-up observations with ground-based telescopes to help identify whether conditions might indeed be suitable for life. &nbsp;</p>
<p>TESS’s cameras are mounted on the top of the satellite and surrounded by a protective cone to shield them from other forms of electromagnetic radiation. Each camera has a 24 by 24 degree view of the sky, large enough to encompass the Orion constellation. The satellite will start its observations in the Southern Hemisphere and will divide the sky into 13 stripes, monitoring each segment for 27 days before pivoting to the next. TESS should be able to observe nearly the entire sky in the Southern Hemisphere in its first year, before moving on to the Northern Hemisphere in its second year.</p>
<p>While TESS points at one stripe of the sky, its cameras will take pictures of the stars in that portion. Ricker and his colleagues have made a list of 200,000 nearby, bright stars that they would particularly want to observe. The satellite’s cameras will create “postage stamp” images that include pixels around each of these stars. These images will be taken every two minutes, in order to maximize the chance of catching the moment that a planet crosses in front of its star. The cameras will also take full-frame images of all the stars in a particular stripe of the sky, every 30 minutes. &nbsp;</p>
<p>“With the two-minute pictures, you can get a movie-like image of what the starlight is doing as the planet is crossing in front of its host star,” Guerrero says. “For the 30-minute images, people are excited about maybe seeing supernovae, asteroids, or counterparts to gravitational waves. We have no idea what we’re going to see at that timescale.”</p>
<p><strong>Are we alone?</strong></p>
<p>After TESS launches, the team expects that the satellite will reestablish contact within the first week, during which it will turn on all its instruments and cameras. Then, there will be a 60-day commissioning phase, as engineers and scientists at Orbital ATK, NASA, and MIT&nbsp;calibrate the instruments and monitor the satellite’s trajectory and performance. After that, TESS will begin to collect and downlink images of the sky. Scientists at MIT and NASA will take the raw data and convert it into light curves that indicate the changing brightness of a star over time.</p>
<p>From there, the TESS Science Team, including Sara Seager, the Class of 1941 Professor of Earth, Atmospheric and Planetary Sciences, and deputy director of science for TESS, will look through thousands of light curves, for at least two similar dips in starlight, indicating that a planet may have passed twice in front of its star. Seager and her colleagues will then employ a battery of methods to determine the mass of a potential planet.</p>
<p>“Mass is a defining planetary characteristic,” Seager says. “If you just know that a planet is twice the size of Earth, it could be a lot of things: a rocky world with a thin atmosphere, or what we call a “mini-Neptune” — a rocky world with a giant gas envelope, where it would be a huge greenhouse blanket, and there would be no life on the surface. So mass and size together give us an average planet density, which tells us a huge amount about what the planet is.”</p>
<p>During TESS’s two-year mission, Seager and her colleagues aim to measure the masses of 50 planets with radii less than four times that of Earth — dimensions that could signal further observations for signs of habitability. Meanwhile, the whole scientific community and public will get a chance to search through TESS data for their own exoplanets. Once the data are calibrated, the team will make them publicly available. Anyone will be able to download the data and draw their own interpretations, including high school students, armchair astronomers, and other research institutions.</p>
<p>With so many eyes on TESS’S data, Seager says there’s a chance that, some day, a nearby planet discovered by TESS might be found to have signs of life.&nbsp;</p>
<p>“There’s no science that will tell us life is out there right now, except that small rocky planets appear to be incredibly common,” Seager says. “They appear to be everywhere we look. So it’s got to be there somewhere.”</p>
<p>TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. George Ricker of MIT’s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission.&nbsp;Additional partners include Orbital ATK, NASA’s Ames Research Center, the Harvard-Smithsonian Center for Astrophysics, and the Space Telescope Science Institute. More than a dozen universities, research institutes, and observatories worldwide are participants in the mission.</p>
A set of flight camera electronics on one of the TESS cameras, developed by the MIT Kavli Institute for Astrophysics and Space Research (MKI), will transmit exoplanet data from the camera to a computer aboard the spacecraft that will process it before transmitting it back to scientists on Earth.Image: MIT Kavli InstituteAstronomy, Astrophysics, Exoplanets, Kavli Institute, Lincoln Laboratory, NASA, National Science Foundation (NSF), Planetary science, Physics, EAPS, Research, Satellites, School of Science, Space, astronomy and planetary science, TESSMeenakshi Chakraborty and Anna Sappington named 2018-2019 Goldwater Scholarshttp://news.mit.edu/2018/meenakshi-chakraborty-anna-sappington-named-goldwater-scholars-0411
Two MIT computer science and molecular biology majors honored for their academic achievements.Wed, 11 Apr 2018 10:25:01 -0400Bendta Schroeder | School of Sciencehttp://news.mit.edu/2018/meenakshi-chakraborty-anna-sappington-named-goldwater-scholars-0411<p>MIT students Meenakshi Chakraborty and Anna Sappington have been named recipients of the Barry Goldwater Scholarship Awards for 2018-2019. They were selected on the basis of academic merit from a field of candidates nominated by university faculty nationwide.</p>
<p>Chakraborty, a junior majoring in computer science and molecular biology, made an early start on biological research at MIT, having reached out to Institute Professor and professor of biology Phillip Sharp for mentorship on a high school report on circular RNA. The quality of her report earned her a place in the Sharp Lab as a Undergraduate Research Opportunities Program researcher during her first year at MIT. Now in her third year, Chakraborty works with mentor Salil Garg to test a theory about how microRNAs regulate embryonic stem cells (ESCs). Garg, Chakraborty, and Sharp propose that a certain understudied set of miRNAs coordinates the expression of key pluripotency genes, whose levels determine ESC behavior and fate.</p>
<p>In the future, Chakraborty plans to continue to pursue her combined interests in computation and molecular biology in doctoral studies, where she hopes to address a fundamental problem pertinent to human health. One faculty advisor wrote that he has “no doubt that she will continue in science at the highest level after her [undergraduate] degree,” describing her as “an extraordinary person; bright and modest, with an ambition to be the best.”</p>
<p>Sappington, a junior majoring in computer science and molecular biology, has worked on three major computational genomics projects in as many years at MIT. The first, now completed, she describes as a “robust computational pipeline for translating genome-wide association studies into real biological insights.” Initially applied to polygenic myocardial infarction and coronary heart disease risks, the methodology can now be applied to a range of high-impact disorders such as schizophrenia, Type 2 diabetes, autism, and cancer. In her current work, Sappington is using neural networks to help build a comprehensive catalog of retinal cell types for the <a href="https://www.broadinstitute.org/research-highlights-human-cell-atlas" target="_blank">Human Cell Atlas</a> in the lab of professor of biology and Broad Institute investigator Aviv Regev. In a 2016 National Institutes of Health summer internship at the National Human Genomic Research Institute, Sappington conducted a third research project in which she demonstrated a fast, alignment-free computational method for identifying orthologs — similar genes from species that are related by descent from a common ancestor.</p>
<p>In the future, Sappington says she hopes to become a physician-scientist with the goal of improving the lives of patients through more personalized medicine. One faculty advisor wrote that she “has that rare combination of intelligence, drive, compassion and interpersonal skills needed to excel at the highest levels,” adding that it is clear she may one day be “a leader in the new field of personalized medicine.”</p>
<p>In addition to MIT’s Goldwater Scholarship recipients, two seniors, physics major Zachary Bogorad and chemical engineering major Janice Ong, were given honorable mentions.</p>
<p>The Barry Goldwater Scholarship and Excellence in Education Program was established by Congress in 1986 to honor Senator Barry Goldwater, who served for 30 years in the U.S. Senate. The program is designed to encourage outstanding students to pursue careers in math, the natural sciences, and engineering. Recipients receive stipends of $7,500 per year toward covering the cost of tuition, fees, books, and room and board.</p>
Meenakshi Chakraborty (left) and Anna SappingtonPhotos courtesy of the students.Awards, honors and fellowships, Students, Undergraduate, Biology, Physics, Chemical engineering, School of Science, School of Engineering, Electrical Engineering & Computer Science (eecs)Dense stellar clusters may foster black hole megamergershttp://news.mit.edu/2018/dense-stellar-clusters-may-foster-black-hole-megamergers-0410
Black holes in these environments could combine repeatedly to form objects bigger than anything a single star could produce.Tue, 10 Apr 2018 11:00:00 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/dense-stellar-clusters-may-foster-black-hole-megamergers-0410<p>When LIGO’s twin detectors first picked up faint wobbles in their respective, identical mirrors, the signal didn’t just provide first direct detection of gravitational waves — it also confirmed the existence of stellar binary black holes, which gave rise to the signal in the first place.</p>
<p>Stellar binary black holes are formed when two black holes, created out of the remnants of massive stars, begin to orbit each other. Eventually, the black holes merge in a spectacular collision that, according to Einstein’s theory of general relativity, should release a huge amount of energy in the form of gravitational waves.</p>
<p>Now, an international team led by MIT astrophysicist Carl Rodriguez suggests that black holes may partner up and merge multiple times, producing black holes more massive than those that form from single stars. These “second-generation mergers” should come from globular clusters — small regions of space, usually at the edges of a galaxy, that are packed with hundreds of thousands to millions of stars.</p>
<p>“We think these clusters formed with hundreds to thousands of black holes that rapidly sank down in the center,” says Carl Rodriguez, a Pappalardo fellow in MIT’s Department of Physics and the Kavli Institute for Astrophysics and Space Research. “These kinds of clusters are essentially factories for black hole binaries, where you’ve got so many black holes hanging out in a small region of space that two black holes could merge and produce a more massive black hole. Then that new black hole can find another companion and merge again.”</p>
<p>If LIGO detects a binary with a black hole component whose mass is greater than around 50 solar masses, then according to the group’s results, there’s a good chance that object arose not from individual stars, but from a dense stellar cluster.</p>
<p>“If we wait long enough, then eventually LIGO will see something that could only have come from these star clusters, because it would be bigger than anything you could get from a single star,” Rodriguez says.&nbsp;</p>
<p>He and his colleagues report their results in a paper appearing in <em>Physical Review Letters</em>.</p>
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<p><strong>Running stars</strong></p>
<p>For the past several years, Rodriguez has investigated the behavior of black holes within globular clusters and whether their interactions differ from black holes occupying less populated regions in space.&nbsp;</p>
<p>Globular clusters can be found in most galaxies, and their number scales with a galaxy’s size. Huge, elliptical galaxies, for instance, host tens of thousands of these stellar conglomerations, while our own Milky Way holds about 200, with the closest cluster residing about 7,000 light years from Earth.</p>
<p>In their new paper, Rodriguez and his colleagues report using a supercomputer called Quest, at Northwestern University, to simulate the complex, dynamical interactions within 24 stellar clusters, ranging in size from 200,000 to 2 million stars, and covering a range of different densities and metallic compositions. The simulations model the evolution of individual stars within these clusters over 12 billion years, following their interactions with other stars and, ultimately, the formation and evolution of the black holes. The simulations also model the trajectories of black holes once they form.</p>
<p>“The neat thing is, because black holes are the most massive objects in these clusters, they sink to the center, where you get a high enough density of black holes to form binaries,” Rodriguez says. “Binary black holes are basically like giant targets hanging out in the cluster, and as you throw other black holes or stars at them, they undergo these crazy chaotic encounters.”</p>
<p><strong>It’s all relative</strong></p>
<p>When running their simulations, the researchers added a key ingredient that was missing in previous efforts to simulate globular clusters. &nbsp;</p>
<p>“What people had done in the past was to treat this as a purely Newtonian problem,” Rodriguez says. “Newton’s theory of gravity works in 99.9 percent of all cases. The few cases in which it doesn’t work might be when you have two black holes whizzing by each other very closely, which normally doesn’t happen in most galaxies.”</p>
<p>Newton’s theory of relativity assumes that, if the black holes were unbound to begin with, neither one would affect the other, and they would simply pass each other by, unchanged. This line of reasoning stems from the fact that Newton failed to recognize the existence of gravitational waves — which Einstein much later predicted would arise from massive orbiting objects, such as two black holes in close proximity.</p>
<p>“In Einstein’s theory of general relativity, where I can emit gravitational waves, then when one black hole passes near another, it can actually emit a tiny pulse of gravitational waves,” Rodriguez explains. “This can subtract enough energy from the system that the two black holes actually become bound, and then they will rapidly merge.”</p>
<p>The team decided to add Einstein’s relativistic effects into their simulations of globular clusters. After running the simulations, they observed black holes merging with each other to create new black holes, inside the stellar clusters themselves. Without relativistic effects, Newtonian gravity predicts that most binary black holes would be kicked out of the cluster by other black holes before they could merge. But by taking relativistic effects into account, Rodriguez and his colleagues found that &nbsp;nearly half of the binary black holes merged inside their stellar clusters, creating a new generation of black holes more massive than those formed from the stars.&nbsp; What happens to those new black holes inside the cluster is a matter of spin.</p>
<p>“If the two black holes are spinning when they merge, the black hole they create will emit gravitational waves in a single preferred direction, like a rocket, creating a &nbsp;new black hole that can shoot out as fast as 5,000 kilometers per second — so, insanely fast,” Rodriguez says. “It only takes a kick of maybe a few tens to a hundred kilometers per second to escape one of these clusters.”</p>
<p>Because of this effect, scientists have largely figured that the product of any black hole merger would get kicked out of the cluster, since it was assumed that most black holes are rapidly spinning.</p>
<p>This assumption, however, seems to contradict the measurements from LIGO, which has so far only detected binary black holes with low spins. To test the implications of this, Rodriguez dialed down the spins of the black holes in his simulations and found that in this scenario, nearly 20 percent of binary black holes from clusters had at least one black hole that was formed in a previous merger. Because they were formed from other black holes, some of these second-generation black holes can be in the range of 50 to 130 solar masses. Scientists believe black holes of this mass cannot form from a single star.</p>
<p>Rodriguez says that if gravitational-wave telescopes such as LIGO detect an object with a mass within this range, there is a good chance that it came not from a single collapsing star, but from a dense stellar cluster.</p>
<p>“My co-authors and I have a bet against a couple people studying binary star formation that within the first 100 LIGO detections, LIGO will detect something within this upper mass gap,” Rodriguez says. “I get a nice bottle of wine if that happens to be true.”</p>
<p>This research was supported in part by the MIT Pappalardo Fellowship in Physics, NASA, the National Science Foundation, the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) at Northwestern University, the Institute of Space Sciences (ICE, CSIC) and Institut d'Estudis Espacials de Catalunya (IEEC), and&nbsp; the Tata Institute of Fundamental Research in Mumbai, India.</p>
A snapshot of a simulation showing a binary black hole formed in the center of a dense star cluster.Image: Northwestern Visualization/Carl RodriguezAstrophysics, Black holes, LIGO, Research, School of Science, Space, astronomy and planetary science, Kavli Institute, National Science Foundation (NSF), NASA, PhysicsBertschinger to leave post as Institute Community and Equity Officerhttp://news.mit.edu/2018/bertschinger-leave-post-institute-community-and-equity-officer-0404
After five years in novel administrative role, MIT physicist will return to faculty responsibilities.Wed, 04 Apr 2018 10:00:00 -0400Peter Dizikes | MIT News Officehttp://news.mit.edu/2018/bertschinger-leave-post-institute-community-and-equity-officer-0404<p>MIT professor Edmund Bertschinger is stepping down from his position as the Institute Community and Equity Officer (ICEO), as he begins a sabbatical this summer.</p>
<p>“I’m very proud to have worked with many dedicated staff across the Institute to help enhance their vision for inclusive excellence at MIT,” Bertschinger says. “MIT has a culture of collaboration, and that applies to diversity, equity, and inclusion as well.”</p>
<p>The announcement was made in a letter to the MIT community from Provost Martin A. Schmidt, who praised Bertschinger’s work in the role. “Thanks to Ed’s leadership, our community has come to embrace a vision of inclusive excellence that honors MIT’s deepest values,” Schmidt wrote.</p>
<p>Bertschinger is the <a href="http://news.mit.edu/2013/bertschinger-named-institute-community-and-equity-officer-0620">first person</a> at MIT to serve as ICEO, a position which was founded in 2013. MIT developed the office to advance activities and conversations in the areas of community, equity, inclusion, and diversity, for students, staff, and faculty.</p>
<p>During Bertschinger’s tenure as ICEO, the office has produced new action on many fronts, including analyzing diversity issues at the Institute, supporting a wide range of new MIT policies, and significantly increasing the number and profile of on-campus events that address diversity issues and lend support to members of the community.</p>
<p>“To help make a better world, we must work continually to make a better MIT,” says President L. Rafael Reif. “I believe that to thrive as a community, we must see our diversity as a welcome, obvious reality and a vital source of our creative strength. We created the role of ICEO to build mutual understanding across the community and to sustain our shared focus on increasing equity and inclusion. I am grateful to Professor Bertschinger for his dedication in taking on this challenge.”</p>
<p>Bertschinger drove the development and release of a <a href="http://news.mit.edu/2015/iceo-report-campus-inclusiveness-0212">2015 report</a>, “Advancing a Respectful and Caring Community: Learning by Doing at MIT,” that evaluated inclusion issues broadly, from the nature of everyday interactions on campus to matters of diversity in faculty hiring.</p>
<p>The report observed that until “we can embrace our diversity, exercise empathy, and advance caring and respect, we will never achieve our full potential as individuals or as an Institute.” The document included recommendations for building community, improving equity, and making structural reforms to enhance inclusiveness.</p>
<p>Under Bertschinger’s watch, updated data on diversity at MIT are also more readily available to the larger community than ever before.</p>
<p>“Ed is never better than when he is advocating for those without a voice, or those less able to speak, including those in our own community,” says MIT Vice President Kirk Kolenbrander. “He placed himself in the middle of many challenges and conversations at MIT, to create real improvement at the Institute.”</p>
<p>Bertschinger also contributed to the development of a long-term engagement between the MIT administration and multiple student groups, including MIT’s Black Students Union (BSU), and the Black Graduate Student Association (BGSA), as well as other members of the MIT community. As a result, after initial meetings in late 2015, the Institute has been acting upon a series of recommendations to implement new programs and resources.</p>
<p>Among other efforts, MIT has enhanced its mental health and counseling services and hired medical staff with expertise in race-based traumatic stress; created ways of making student orientation more inclusive and added implicit bias training to many areas of MIT; increased student financial aid by $23.4 million over two years; and collected and shared relevant data more widely.&nbsp;</p>
<p><br />
“At MIT, we are not afraid to look at ourselves,” says DiOnetta Jones Crayton, MIT’s associate dean for undergraduate education and director of the Office of Minority Education. “Since the creation of the ICEO, we have seen much more open dialogue and discussion on issues related to diversity, inclusion, and equity. Ed Bertschinger’s leadership, along with the efforts of many groups on campus, has helped bring the community together to talk about these issues. We have made significant progress in many areas, but we must continue to build upon these efforts. There is more work to be done.”</p>
<p>As ICEO, Bertschinger ensured that his office had a multifaceted role, connecting with all parts of the MIT community and helping to raise the profile of many groups working for greater campus inclusion.</p>
<p>“For almost five years the ICEO has played an&nbsp;integral part in advancing issues of equity, inclusion, and social justice at&nbsp;MIT,” says Abigail Francis, director of LBGT Services at MIT.&nbsp;“During this time Ed and&nbsp;the ICEO&nbsp;office have been a critical source of visibility, resources, and support for the&nbsp;LBGTQ+ community.&nbsp;As one of the only&nbsp;centralized&nbsp;resources for equity and inclusion efforts, and as one of very few&nbsp;areas of broad-based support for marginalized populations, the ICEO has become&nbsp;an&nbsp;essential part of MIT’s mission.”</p>
<p>In addition to working on behalf of students and faculty, Bertschinger also saw himself as an advocate for MIT’s staff, and sought to ensure that staff members were equal partners in the Institute’s inclusion efforts.</p>
<p>“For the last nine years, I have had the privilege of working with Ed Bertschinger,” says Alyce Johnson, MIT’s manager of staff diversity and inclusion. “I appreciate Ed's contribution as ICEO; he brought a coordinating and reflective voice. His openness, support, and commitment to all members of the community made a difference. His leadership has been critical to advancing diversity, inclusion, social justice, and belonging to our community.”</p>
<p>Bertschinger received his BS in physics from Caltech in 1979, and his PhD in astrophysical sciences from Princeton University in 1984. He was a postdoc at the University of Virginia and a research fellow at the University of California at Berkeley before joining the MIT faculty in 1986. He served as head of the MIT Department of Physics from 2008 until 2013.</p>
<p>Reflecting on the advances the Institute has made during his time as ICEO, Bertschinger says that, speaking broadly, his main achievement is “to have helped change expectations around diversity, equity, and inclusion across MIT,” adding that a focus on these issues is “now a part of our institutional DNA.”</p>
<p>And, noting the surge in campus events dedicated to diversity and inclusion, developed by both the administration and student groups, Bertschinger notes that “the community has come to expect this level of engagement,” and now has many more opportunities for “candid conversations about race, gender, sexual harassment, inclusion, and what it really means to make a better world.”</p>
<p>In his letter to the MIT community, Schmidt described the next steps to fill the ICEO position: “In keeping with the importance of the role, the next ICEO will also be an MIT faculty member. As I begin the search process, I welcome your perspective and suggestions. Please write to <a href="mailto:iceosearch@mit.edu">iceosearch@mit.edu</a>. I will treat any correspondence as confidential.”</p>
Image: Jose-Luis OlivaresDiversity and inclusion, Leadership, Letters to the Community, Provost, Faculty, Students, Staff, Administration, Physics, Community, President L. Rafael ReifSchool of Science announces Infinite Mile Awards for 2018http://news.mit.edu/2018/school-of-science-infinite-mile-awards-0403
Seven staff members honored for their outstanding contributions to the MIT community.Tue, 03 Apr 2018 16:10:01 -0400School of Sciencehttp://news.mit.edu/2018/school-of-science-infinite-mile-awards-0403<p>The MIT School of Science has announced seven winners of the Infinite Mile Award for 2018. The award will be presented at a luncheon this May in recognition of staff members whose accomplishments and contributions to their departments, laboratories, and centers far exceed expectations.</p>
<p>The 2018 Infinite Mile Award winners are:</p>
<p>Hristina Dineva, Department of Biology;</p>
<p>Theresa Cummings, Department of Mathematics;</p>
<p>Mary Gallagher, Department of Biology;</p>
<p>Jack McGlashing, Laboratory for Nuclear Science;</p>
<p>Sydney Miller, Department of Physics;</p>
<p>Miroslava Parsons, Department of Earth, Atmospheric and Planetary Sciences; and</p>
<p>Alexandra Sokhina, Simons Center for the Social Brain.</p>
<p>The awards luncheon will also honor winners of last fall’s Infinite Kilometer Award, which was established to highlight and reward the extraordinary — but often underrecognized — work of the school’s research staff and postdoctoral researchers.</p>
<p>The&nbsp;2017 Infinite Kilometer winners are:</p>
<p>Rodrigo Garcia, McGovern Institute for Brain Research;</p>
<p>Lydia Herzel, Department of Biology;</p>
<p>Yutaro Iiyama, Laboratory for Nuclear Science;</p>
<p>Kendrick Jones, Picower Institute for Learning and Memory;</p>
<p>Matthew Musgrave, Laboratory for Nuclear Science;</p>
<p>Cody Siciliano, Picower Institute for Learning and Memory;</p>
<p>Peter Sudmant, Department of Biology; and</p>
<p>Ashley Watson, Picower Institute for Learning and Memory.</p>
Photo: Christopher HartingAwards, honors and fellowships, School of Science, Staff, Graduate, postdoctoral, Community, Biology, Mathematics, Laboratory for Nuclear Science, Physics, EAPS, McGovern Institute, Picower InstituteEngineers turn plastic insulator into heat conductorhttp://news.mit.edu/2018/engineers-turn-plastic-insulator-heat-conductor-0330
Technique could prevent overheating of laptops, mobile phones, and other electronics.Fri, 30 Mar 2018 14:00:00 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/engineers-turn-plastic-insulator-heat-conductor-0330<p>Plastics are excellent insulators, meaning they can efficiently trap heat — a quality that can be an advantage in something like a coffee cup sleeve. But this insulating property is less desirable in products such as plastic casings for laptops and mobile phones, which can overheat, in part because the coverings trap the heat that the devices produce.</p>
<p>Now a team of engineers at MIT has developed a polymer thermal conductor — a plastic material that, however counterintuitively, works as a heat conductor, dissipating heat rather than insulating it. The new polymers, which are lightweight and flexible, can conduct 10 times as much heat as most commercially used polymers.</p>
<p>“Traditional polymers are both electrically and thermally insulating. The discovery and development of electrically conductive polymers has led to novel electronic applications such as flexible displays and wearable biosensors,” says Yanfei Xu, a postdoc in MIT’s Department of Mechanical Engineering. “Our polymer can thermally conduct and remove heat much more efficiently. We believe polymers could be made into next-generation heat conductors for advanced thermal management applications, such as a self-cooling alternative to existing electronics casings.”</p>
<p>Xu and a team of postdocs, graduate students, and faculty, have published their results today in <em>Science Advances</em>. The team includes Xiaoxue Wang, who contributed equally to the research with Xu, along with Jiawei Zhou, Bai Song, Elizabeth Lee, and Samuel Huberman; Zhang Jiang, physicist at Argonne National Laboratory; Karen Gleason, associate provost of MIT and the Alexander I. Michael Kasser Professor of Chemical Engineering; and Gang Chen, head of MIT’s Department of Mechanical Engineering and the Carl Richard Soderberg Professor of Power Engineering.</p>
<p><strong>Stretching spaghetti</strong></p>
<p>If you were to zoom in on the microstructure of an average polymer, it wouldn’t be difficult to see why the material traps heat so easily. At the microscopic level, polymers are made from long chains of monomers, or molecular units, linked end to end. These chains are often tangled in a spaghetti-like ball. Heat carriers have a hard time moving through this disorderly mess and tend to get trapped within the polymeric snarls and knots.</p>
<p>And yet, researchers have attempted to turn these natural thermal insulators into conductors. For electronics, polymers would offer a unique combination of properties, as they are lightweight, flexible, and chemically inert. Polymers are also electrically insulating, meaning they do not conduct electricity, and can therefore be used to prevent devices such as laptops and mobile phones from short-circuiting in their users’ hands.</p>
<p>Several groups have engineered polymer conductors in recent years, including Chen’s group, which in 2010 invented a method to create “ultradrawn nanofibers” from a standard sample of polyethylene. The technique stretched the messy, disordered polymers into ultrathin, ordered chains — much like untangling a string of holiday lights. Chen found that the resulting chains enabled heat to skip easily along and through the material, and that the polymer conducted 300 times as much heat compared with ordinary plastics.</p>
<p>But the insulator-turned-conductor could only dissipate heat in one direction, along the length of each polymer chain. Heat couldn’t travel between polymer chains, due to weak Van der Waals forces — a phenomenon that essentially attracts two or more molecules close to each other. Xu wondered whether a polymer material could be made to scatter heat away, in all directions.</p>
<p>Xu conceived of the current study as an attempt to engineer polymers with high thermal conductivity, by simultaneously engineering intramolecular and intermolecular forces — a method that she hoped would enable efficient heat transport along and between polymer chains.</p>
<p>The team ultimately produced a heat-conducting polymer known as polythiophene, a type of conjugated polymer that is commonly used in many electronic devices.</p>
<p><strong>Hints of heat in all directions</strong></p>
<p>Xu, Chen, and members of Chen’s lab teamed up with Gleason and her lab members to develop a new way to engineer a polymer conductor using oxidative chemical vapor deposition (oCVD), whereby two vapors are directed into a chamber and onto a substrate, where they interact and form a film. “Our reaction was able to create rigid chains of polymers, rather than the twisted, spaghetti-like strands in normal polymers.” Xu says.</p>
<p>In this case, Wang flowed the oxidant into a chamber, along with a vapor of monomers — individual molecular units that, when oxidized, form into the chains known as polymers.</p>
<p>“We grew the polymers on silicon/glass substrates, onto which the oxidant and monomers are adsorbed and reacted, leveraging the unique self-templated growth mechanism of CVD technology," Wang says.</p>
<p>Wang produced relatively large-scale samples, each measuring 2 square centimeters — about the size of a thumbprint.</p>
<p>“Because this sample is used so ubiquitously, as in solar cells, organic field-effect transistors, and organic light-emitting diodes, if this material can be made to be thermally conductive, it can dissipate heat in all organic electronics,” Xu says.</p>
<p>The team measured each sample’s thermal conductivity using time-domain thermal reflectance — a technique in which they shoot a laser onto the material to heat up its surface and then monitor the drop in its surface temperature by measuring the material’s reflectance as the heat spreads into the material.</p>
<p>“The temporal profile of the decay of surface temperature is related to the speed of heat spreading, from which we were able to compute the thermal conductivity,” Zhou says.</p>
<p>On average, the polymer samples were able to conduct heat at about 2 watts per meter per kelvin — about 10 times faster than what conventional polymers can achieve. At Argonne National Laboratory, Jiang and Xu found that polymer samples appeared nearly isotropic, or uniform. This suggests that the material’s properties, such as its thermal conductivity, should also be nearly uniform. Following this reasoning, the team predicted that the material should conduct heat equally well in all directions, increasing its heat-dissipating potential.</p>
<p>Going forward, the team will continue exploring the fundamental physics behind polymer conductivity, as well as ways to enable the material to be used in electronics and other products, such as casings for batteries, and films for printed circuit boards.</p>
<p>“We can directly and conformally coat this material onto silicon wafers and different electronic devices” Xu says. “If we can understand how thermal transport [works] in these disordered structures, maybe we can also push for higher thermal conductivity. Then we can help to resolve this widespread overheating problem, and provide better thermal management.”</p>
<p>This research was supported, in part, by the U.S. Department of Energy — Basic Energy Sciences and the MIT Deshpande Center.</p>
Image: Chelsea Turner/MITBatteries, electronics, Photonics, Photovoltaics, Energy, Mechanical engineering, Chemical engineering, Materials Science and Engineering, Chemistry, Physics, Research, School of Engineering, School of Science, Department of Energy (DoE)Scientists find different cell types contain the same enzyme ratioshttp://news.mit.edu/2018/scientists-find-different-cell-types-contain-same-enzyme-ratios-0329
New discovery suggests that all life may share a common design principle.Thu, 29 Mar 2018 12:00:00 -0400Justin Chen | Department of Biologyhttp://news.mit.edu/2018/scientists-find-different-cell-types-contain-same-enzyme-ratios-0329<p>By studying bacteria and yeast, researchers at MIT have discovered that vastly different types of cells still share fundamental similarities, conserved across species and refined over time. More specifically, these cells contain the same proportion of specialized proteins, known as enzymes, which coordinate chemical reactions within the cell.</p>
<p>To grow and divide, cells rely on a unique mixture of enzymes that perform millions of chemical reactions per second. Many enzymes, working in relay, perform a linked series of chemical reactions called a “pathway,” where the products of one chemical reaction are the starting materials for the next. By making many incremental changes to molecules, enzymes in a pathway perform vital functions such as turning nutrients into energy or duplicating DNA.</p>
<p>For decades, scientists wondered whether the relative amounts of enzymes in a pathway were tightly controlled in order to better coordinate their chemical reactions. Now, researchers have demonstrated that cells not only produce precise amounts of enzymes, but that evolutionary pressure selects for a preferred ratio of enzymes. In this way, enzymes behave like ingredients of a cake that must be combined in the correct proportions and all life may share the same enzyme recipe.</p>
<p>“We still don’t know why this combination of enzymes is ideal,” says Gene-Wei Li, assistant professor of biology at MIT, “but this question opens up an entirely new field of biology that we’re calling systems level optimization of pathways. In this discipline, researchers would study how different enzymes and pathways behave within the complex environment of the cell.”</p>
<p>Li is the senior author of the study, which appears online in the journal <em>Cell</em> on March 29, and in print on April 19. The paper’s lead author, Jean-Benoît Lalanne, is a graduate student in the MIT Department of Physics.</p>
<p><strong>An unexpected observation</strong></p>
<p>For more than 100 years, biologists have studied enzymes by watching them catalyze chemical reactions in test tubes, and — more recently — using X-rays to observe their molecular structure.</p>
<p>And yet, despite years of work describing individual proteins in great detail, scientists still don’t understand many of the basic properties of enzymes within the cell. For example, it is not yet possible to predict the optimal amount of enzyme a cell should make to maximize its chance of survival.</p>
<p>The calculation is tricky because the answer depends not only on the specific function of the enzyme, but also how its actions may have a ripple effect on other chemical reactions and enzymes within the cell.</p>
<p>“Even if we know exactly what an enzyme does,” Li says, “we still don’t have a sense for how much of that protein the cell will make. Thinking about biochemical pathways is even more complicated. If we gave biochemists three enzymes in a pathway that, for example, break down sugar into energy, they would probably not know how to mix the proteins at the proper ratios to optimize the reaction.”</p>
<p>The study of the relative amounts of substances — including proteins — is known as “stoichiometry.” To investigate the stoichiometry of enzymes in different types of cells, Li and his colleagues analyzed three different species of bacteria — <em>Escherichia</em> <em>coli,</em> <em>Bacillus</em><em> subtilis,</em> and <em>Vibrio</em> <em>natriegens — </em>as well as the budding yeast <em>Saccharomyces</em><em> cerevisiae.</em> Among these cells, scientists compared the amount of enzymes in 21 pathways responsible for a variety of tasks including repairing DNA, constructing fatty acids, and converting sugar to energy. Because these species of yeast and bacteria have evolved to live in different environments and have different cellular structures, such as the presence or lack of a nucleus, researchers were surprised to find that all four cells types had nearly identical enzyme stoichiometry in all pathways examined.</p>
<p>Li’s team followed up their unexpected results by detailing how bacteria achieve a consistent enzyme stoichiometry. Cells control enzyme production by regulating two processes. The first, transcription, converts the information contained in a strand of DNA into many copies of messenger RNA (mRNA). The second, translation, occurs as ribosomes decode the mRNAs to construct proteins. By analyzing transcription across all three bacterial species, Li’s team discovered that the different bacteria produced varying amounts of mRNA encoding for enzymes in a pathway.</p>
<p>Different amounts of mRNA theoretically lead to differences in protein production, but the researchers found instead that the cells adjusted their rates of translation to compensate for changes in transcription. Cells that produced more mRNA slowed their rates of protein synthesis, while cells that produced less mRNA increased the speed of protein synthesis. Thanks to this compensation, the stoichiometry of enzymes remained constant across the different bacteria.</p>
<p>“It is remarkable that <em>E. coli</em> and <em>B. subtilis </em>need the same relative amount of the corresponding proteins, as seen by the compensatory variations in transcription and translation efficiencies,” says Johan Elf, professor of physical biology at Uppsala University in Sweden. “These results raise interesting questions about how enzyme production in different cells have evolved."</p>
<p>“Examining bacterial gene clusters was really striking,” lead author Lalanne says. “Over a long evolutionary history, these genes have shifted positions, mutated into different sequences, and been bombarded by mobile pieces of DNA that randomly insert themselves into the genome. Despite all this, the bacteria have compensated for these changes by adjusting translation to maintain the stoichiometry of their enzymes. This suggests that evolutionary forces, which we don’t yet understand, have shaped cells to have the same enzyme stoichiometry.”<br />
<br />
<strong>Searching for the stoichiometry regulating human health</strong></p>
<p>In the future, Li and his colleagues will test whether their findings in bacteria and yeast extend to humans. Because unicellular and multicellular organisms manage energy and nutrients differently, and experience different selection pressures, researchers are not sure what they will discover.</p>
<p>“Perhaps there will be enzymes whose stoichiometry varies, and a smaller subset of enzymes whose levels are more conserved,” Li says. “This would indicate that the human body is sensitive to changes in specific enzymes that could make good drug targets. But we won’t know until we look.”</p>
<p>Beyond the human body, Li and his team believe that it is possible to find simplicity underlying the complex bustle of molecules within all cells. Like other mathematical patterns in nature, such as the the spiral of seashells or the branching pattern of trees, the stoichiometry of enzymes may be a widespread design principle of life.</p>
<p>The research was funded by the National Institutes of Health, Pew Biomedical Scholars Program, Sloan Research Fellowship, Searle Scholars Program, National Sciences and Engineering Research Council of Canada, Howard Hughes Medical Institute, National Science Foundation, Helen Hay Whitney Foundation, Jane Coffin Childs Memorial Fund, and the Smith Family Foundation.</p>
MIT researchers have discovered that enzymes performing the same function in yeast and bacteria may have different structures, but are present in the same relative amounts within each type of cell.Image: Haynathart/Wikimedia CommonsResearch, Bacteria, Biology, Evolution, Genetics, Microbes, Physics, DNA, RNA, School of ScienceCenter for Theoretical Physics celebrates 50 yearshttp://news.mit.edu/2018/mit-center-theoretical-physics-marks-50th-anniversary-symposium-looking-present-and-future-0328
Symposium explores how novel ideas and experiments are advancing many areas of theoretical physics in newly interconnected ways.Wed, 28 Mar 2018 16:00:00 -0400Scott Morley | Center for Theoretical Physicshttp://news.mit.edu/2018/mit-center-theoretical-physics-marks-50th-anniversary-symposium-looking-present-and-future-0328<p>To celebrate the 50th anniversary of its founding, the Center for Theoretical Physics (CTP) hosted a symposium on Saturday, March 24. "CTP50: The Center for Theoretical Physics: The First Fifty Years" brought together present and former members of the CTP as well as friends, supporters, and others interested in the past, present, and future of theoretical physics.</p>
<p>The celebration of 50 years of physics at the CTP featured speakers that included former&nbsp;students, postdocs, and faculty as well as some current CTP faculty members. Some of the key topics explored at the symposium included gravitational waves, black holes, dark matter, neutron stars, and nuclear physics; dualities and symmetries in string theory, condensed matter physics, and quantum field theory; quantum information and computing; and the foundations of quantum physics. Presentations on recent work in these areas were interspersed with historical perspectives and recollections of the CTP's last 50 years, discussion and videos illustrating the current activities in the CTP, and speculations regarding future directions in theoretical physics.</p>
<p>"In its 50 years, the CTP has seen its faculty, postdocs, and students make discoveries that have advanced our theoretical understanding of how the universe works," Michael Sipser,&nbsp;Dean of the School of Science, said in his&nbsp;introductory comments to lead off the day.&nbsp;"Now we have a new group of young faculty poised to make discoveries into the nature of the universe in areas such as dark matter —&nbsp;the unknown substance that comprises more than 80 percent of the matter in the universe."</p>
<p>The afternoon session was led off by remarks from George Fai from the Office of Nuclear Physics in the U.S.&nbsp;Department of Energy (DOE) who read a congratulatory letter from Tim Hallman, the associate director of the DOE Office of Science.&nbsp;Fai's remarks were followed by commentary from&nbsp;Laboratory from Nuclear Science (LNS) Director Bolek Wyslouch. The CTP is a part of LNS, and Wyslouch commented on the increased level of collaboration between young faculty in nuclear and particle physics, in both theoretical and experimental work.</p>
<p>David Kaiser, the Germeshausen Professor of the History of Science and a professor of physics, also&nbsp;gave an engaging history of the founding of the Center for Theoretical Physics in a talk entitled: "It was Fifty Years Ago Today ... A Brief Look Back at Physics, MIT and the World of 1968."&nbsp;The CTP was founded in 1968 under its first director, Herman Feshbach, while Viki Weisskopf was the head of the Department of Physics.&nbsp;In his talk, Kaiser traced the development of theoretical physics, beginning with mathematicians-astronomers-philosophers Galileo and Newton, and highlighted the relatively recent development of the notion of "theoretical physicist" as a job title.&nbsp;The CTP&nbsp;as an institute of theoretical physics was one of the first such centers in the United States.</p>
<p>The recent observation of gravitational waves from mergers of black holes and neutron stars by the LIGO experiment (for which MIT's Rai Weiss received the 2017 Nobel prize) occurred more than&nbsp;100 years after Einstein's development of the theory of general relativity, which predicts gravitational waves that carry energy across space.&nbsp;This observation has in turn stimulated new developments in theory.&nbsp;Chung Pei-Ma SB '93 PhD '96, who is now&nbsp;the Judy Chandler Webb Professor of Astronomy and Physics at the&nbsp;University of California at Berkeley,&nbsp;described new progress in identifying supermassive black holes at the centers of distant galaxies, and the prospects for detecting gravitational wave signals from mergers of these objects.&nbsp;Sanjay Reddy, a former CTP postdoc who is now a professor at the Institute for Nuclear Theory at the University of Washington,&nbsp;described how combined gravitational and electromagnetic signals from a neutron star merger observed late last year have provided important new information that helps describe nuclear matter at the highest achievable densities, as well as how heavy elements such as gold and platinum are produced in the universe.</p>
<p>The mystery of dark matter, which constitutes roughly 80 percent&nbsp;of the mass density of the universe, also provided substantial material for discussion.&nbsp;MIT/CTP Nobel laureate Frank Wilczek described in an entertaining talk how he named the "axion" particle, which is a likely dark matter candidate, after a laundry detergent. Former CTP faculty member Lisa Randall, now the Frank B. Baird, Jr., Professor of Science at Harvard,&nbsp;spoke about some new ideas about dark matter, in particular about&nbsp;dark matter particles that may interact with one another.&nbsp;CTP faculty members Will Detmold, Tracy Slatyer, and Jesse Thaler, as well as experimentalist Lindley Winslow from LNS, were featured in the premiere of a new video directed by Bill Lattanzi on efforts at MIT to understand and discover dark matter.</p>
<p>Another theme at the symposium was the development of new approaches to understanding quantum field theories, combining methodology from string theory with insights from condensed matter physics.&nbsp;Former CTP postdoc Dam Son, who is now a University Professor at the&nbsp;University of Chicago, described a new theoretical description of a fractional quantum Hall fluid, a special topological state of matter, in terms of composite fermions with equivalent (dual) descriptions in which a particle density in one description becomes a magnetic field in the other, and vice versa.&nbsp;Former MIT Pappalardo Fellow David Tong, a professor of theoretical physics at Cambridge University, using methods motivated from string theory,&nbsp;showed&nbsp;how this was just one among a web of dualities, permitting descriptions of condensed matter systems in terms of very different kinds of field theories,&nbsp;and how these dualities are giving new insights into the structure of quantum field theory in general. Another former Pappalardo Fellow, University of Michigan professor of physics Henriette Elvang, showed how a different novel approach to quantum field theory based on scattering amplitudes can place strong constraints on what kinds of effective&nbsp;theories of low-energy excitations can be consistent in the presence of broken symmetries, relating to the famous work of emeritus CTP faculty member Jeffrey Goldstone in 1961 that led to the Higgs mechanism and the standard model of particle physics. Frank Wilczek also described new ideas about broken time symmetries in quantum field theory, leading to new states of matter called "time crystals" that may lead to new kinds of precision sensors.</p>
<p>Quantum theory —&nbsp;including quantum computing, quantum information, connections to quantum gravity, and its foundations —&nbsp;was another focal point of interest at the symposium.&nbsp;Andrew Childs Phd '04,&nbsp;now professor of computer science at the University of Maryland,&nbsp;described efficient methods for simulating quantum physics on quantum computers. Bill Lattanzi also premiered a&nbsp;second new video&nbsp;featuring CTP faculty members Daniel Harlow and Aram Harrow and their work on quantum error correction and black hole physics and the connections between these ideas.&nbsp;CTP professor Alan Guth spoke on the Cosmic Bell Experiment, a test of quantum entanglement, and Einstein's "spooky action at a distance," which makes use of some of the oldest light in the universe to address a loophole in previous experiments to test the foundations of quantum theory.</p>
<p>Finally, a panel on the future of theoretical physics featured a&nbsp;lively engagement among the most recent generation of CTP faculty including&nbsp;professors William Detmold, Aram Harrow, Daniel Harlow,&nbsp;Tracy Slatyer,&nbsp;and Jesse Thaler.&nbsp;Some of this discussion focused on the way in which current developments in theory are bringing together once disparate disciplines such as string theory, field theory, nuclear physics, and condensed matter theory in new ways, and ways in which theoretical physicists are getting more closely involved with experiment as large amounts of data become available from particle physics and astrophysics observations.&nbsp;Another theme was the increasing role of large-scale computing in theoretical physics, from lattice QCD, which uses large computers to solve difficult problems of nuclear interactions, to machine learning, which is increasingly used in theoretical and experimental physics, and quantum computing, which may, as Richard Feynman originally suggested, eventually be the most effective way of analyzing real or hypothetical quantum systems.</p>
<p>A theme throughout the day, with many former students and postdocs returning to the CTP, was the important role of interactions and community within the theoretical physics group.&nbsp;A <a href="https://www.youtube.com/watch?v=L0BPTH_oerc">video by Lillie Paquette</a> illustrated the unified research and teaching environment in the CTP, made possible with the 2008 renovation when the Elings Center for Theoretical Physics in the Green Center was constructed.&nbsp;</p>
<p>Another video made by Harry Bechkes was also premiered, showing the novel ways in which CTP faculty members&nbsp;Iain Stewart and Barton Zwiebach are using new technologies developed together with the&nbsp;Office of Digital Learning (led by CTP faculty member and Dean for Digital Learning Krishna Rajagopal) to enhance the teaching of MIT students learning effective field theory and quantum mechanics on campus by blending online and in-class education, while at the same time teaching learners around the globe and shaping the future of their disciplines.</p>
<p>At a celebratory dinner at the Samberg Center, several speakers commented on different aspects of the CTP history and culture.&nbsp;Professor Ernest Moniz — who has served as a CTP faculty member, department head for Physics, director of the MIT Energy Initiative, and US. Secretary of Energy during the Obama Administration —&nbsp;emphasized the commitment to social responsibility that has played an important role in the CTP and strongly influenced his career. This ranged from&nbsp;the involvement of CTP founders Herman Feshbach and Francis Low with the Union of Concerned Scientists, which decried military research at MIT and sought to aid silenced researchers behind the Iron Curtain&nbsp;like&nbsp;Andrei Sakharov, to recent examples such as the newly released book "The Physics of Energy" by the CTP's former director Robert Jaffe and its current director Washington Taylor, which gives a unified perspective on physics through the theme of energy and its role and impact on our world.&nbsp;</p>
<p>The evening concluded with remarks by Harvard Professor Cumrun Vafa '81, who&nbsp;shared stories of the generous and open environment among the math and physics faculty during his formative time at MIT. Vafa&nbsp;echoed&nbsp;the sentiments of many of the symposium attendees, who had fond recollections of their undergraduate, graduate, and&nbsp;postdoc years at the center.</p>
CTP Professors Hong Liu, Jesse Thaler, William Detmold, Daniel Harlow, Tracy Slatyer, and Aram Harrow share a moment during a panel discussion on the future of theoretical physics.Photo: Justin KnightSchool of Science, Physics, Laboratory for Nuclear Science, Department of Energy (DoE), Faculty, History of MIT, Machine learning, Nuclear science and engineering, Quantum computing, Special events and speakers, Astrophysics, Black holes, Center for Theoretical PhysicsScientists report first results from CUORE neutrino experimenthttp://news.mit.edu/2018/scientists-report-first-results-neutrino-mountain-experiment-matter-antimatter-0326
Data could shed light on why the universe has more matter than antimatter.Mon, 26 Mar 2018 15:30:00 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/scientists-report-first-results-neutrino-mountain-experiment-matter-antimatter-0326<p>This week, an international team of physicists, including researchers at MIT, is reporting the first results from an underground experiment designed to answer one of physics’ most fundamental questions: Why is our universe made mostly of matter?&nbsp;&nbsp;</p>
<p>According to theory, the Big Bang should have produced equal amounts of matter and antimatter — the latter consisting of “antiparticles” that are essentially mirror images of matter, only bearing charges opposite to those of protons, electrons, neutrons, and other particle counterparts. And yet, we live in a decidedly material universe, made mostly of galaxies, stars, planets, and everything we see around us — and very little antimatter.</p>
<p>Physicists posit that some process must have tilted the balance in favor of matter during the first moments following the Big Bang. One such theoretical process involves the neutrino — a particle that, despite having almost no mass and interacting very little with other matter, is thought to permeate the universe, with trillions of the ghostlike particles streaming harmlessly through our bodies every second.</p>
<p>There is a possibility that the neutrino may be its own antiparticle, meaning that it may have the ability to transform between a matter and antimatter version of itself. If that is the case, physicists believe this might explain the universe’s imbalance, as heavier neutrinos, produced immediately after the Big Bang, would have decayed asymmetrically, producing more matter, rather than antimatter, versions of themselves.</p>
<p>One way to confirm that the neutrino is its own antiparticle, is to detect an exceedingly rare process known as a “neutrinoless double-beta decay,” in which a stable isotope, such as tellurium or xenon, gives off certain particles, including electrons and antineutrinos, as it naturally decays. If the neutrino is indeed its own antiparticle, then according to the rules of physics the antineutrinos should cancel each other out, and this decay process should be “neutrinoless.” Any measure of this process should only record the electrons escaping from the isotope.</p>
<p>The underground experiment known as CUORE, for the Cryogenic Underground Observatory for Rare Events, is designed to detect a neutrinoless double-beta decay from the natural decay of 988 crystals of tellurium dioxide. In a paper published this week in <em>Physical Review Letters</em>, researchers, including physicists at MIT, report on the first two months of data collected by CUORE (Italian for “heart”). And while they have not yet detected the telltale process, they have been able to set the most stringent limits yet on the amount of time that such a process should take, if it exists at all. Based on their results, they estimate that a single atom of tellurium should undergo a neutrinoless double-beta decay, at most, once every 10 septillion (1 followed by 25 zeros) years.</p>
<p>Taking into account the massive number of atoms within the experiment’s 988 crystals, the researchers predict that within the next five years they should be able to detect at least five atoms undergoing this process, if it exists, providing definitive proof that the neutrino is its own antiparticle.</p>
<p>“It’s a very rare process — if observed, it would be the slowest thing that has ever been measured,” says CUORE member Lindley Winslow, a member of the Laboratory for Nuclear Science, and the Jerrold R. Zacharias Career Development Assistant Professor of Physics at MIT, who led the analysis. “The big excitement here is that we were able to run 998 crystals together, and now we’re on a path to try and see something.”</p>
<p>The CUORE collaboration includes some 150 scientists primarily from Italy and the U.S., including Winslow and a small team of postdocs and graduate students from MIT.</p>
<p><strong>Coldest cube in the universe</strong></p>
<p>The CUORE experiment is housed underground, in the Italian National Institute for Nuclear Physics’ (INFN) Gran Sasso National Laboratories, buried deep within a mountain in central Italy, in order to shield it from external stimuli such as the constant bombardment of radiation from sources in the universe.</p>
<p>The heart of the experiment is a detector consisting of 19 towers, each containing 52 cube-shaped crystals of tellurium dioxide, totaling 988 crystals in all, with a mass of about 742 kilograms, or 1,600 pounds. Scientists estimate that this amount of crystals embodies around 100 septillion atoms of the particular tellurium isotope. Electronics and temperature sensors are attached to each crystal to monitor signs of their decay.</p>
<p>The entire detector resides within an ultracold refrigerator, about the size of a vending machine, which maintains a steady temperature of 6 millikelvin, or -459.6 degrees Fahrenheit. Researchers in the collaboration have previously calculated that this refrigerator is the coldest cubic meter that exists in the universe. &nbsp;&nbsp;</p>
<p>The experiment needs to be kept exceedingly cold in order to detect minute changes in temperature generated by the decay of a single tellurium atom. In a normal double-beta decay process, a tellurium atom gives off two electrons, as well as two antineutrinos, which amount to a certain energy in the form of heat. In the event of a neutrinoless double-beta decay, the two antineutrinos should cancel each other out, and only the energy released by the two electrons would be generated. Physicists have previously calculated that this energy must be around 2.5 megaelectron volts (Mev).</p>
<p>In the first two months of CUORE’s operation, scientists have essentially been taking the temperature of the 988 tellurium crystals, looking for any miniscule spike in energy around that 2.5 Mev mark.</p>
<p>“CUORE is like a gigantic thermometer,” Winslow says. “Whenever you see a heat deposit on a crystal, you end up seeing a pulse that you can digitize. Then you go through and look at these pulses, and the height and width of the pulse corresponds to how much energy was there. Then you zoom in and count how many events were at 2.5 Mev, and we basically saw nothing. Which is probably good because we weren’t expecting to see anything in the first two months of data.”</p>
<p><strong>The heart will go on</strong></p>
<p>The results more or less indicate that, within the short window in which CUORE has so far operated, not one of the 1,000 septillion tellurium atoms in the detector underwent a neutrinoless double-beta decay. Statistically speaking, this means that it would take at least 10 septillion years, or &nbsp;years, for a single atom to undergo this process if a neutrino is in fact its own antiparticle.</p>
<p>“For tellurium dioxide, this is the best limit for the lifetime of this process that we’ve ever gotten,” Winslow says.</p>
<p>CUORE will continue to monitor the crystals for the next five years, and researchers are now designing the experiment’s next generation, which they have dubbed CUPID — a detector that will look for the same process within an even greater number of atoms. Beyond CUPID, Winslow says there is just one more, bigger iteration that would be possible, before scientists can make a definitive conclusion.</p>
<p>“If we don’t see it within 10 to 15 years, then, unless nature chose something really weird, the neutrino is most likely not its own antiparticle,” Winslow says. “Particle physics tells you there’s not much more wiggle room for the neutrino to still be its own antiparticle, and for you not to have seen it. There’s not that many places to hide.”</p>
<p>This research is supported by the National Institute for Nuclear Physics (INFN) in Italy, the National Science Foundation, the Alfred P. Sloan Foundation, and the U.S. Department of Energy.</p>
Bottom view of the 19 CUORE towers installed in the cryostat.Image: CUORE CollaborationPhysics, Research, School of Science, Astrophysics, National Science Foundation (NSF), Department of Energy (DoE), Nuclear science, Laboratory for Nuclear Science, NeutrinosMIT graduate engineering, business, science programs ranked highly by U.S. News for 2019http://news.mit.edu/2018/graduate-engineering-business-science-programs-ranked-highly-us-news-0320
Graduate engineering program is No. 1 in the nation; MIT Sloan is No. 5.Tue, 20 Mar 2018 00:01:00 -0400MIT News Officehttp://news.mit.edu/2018/graduate-engineering-business-science-programs-ranked-highly-us-news-0320<p>MIT’s graduate program in engineering has again earned a No. 1 spot in <em>U.S. News</em><em> and World Report’s</em> annual rankings, a place it has held since 1990, when the magazine first ranked such programs.</p>
<p>The MIT Sloan School of Management also placed highly, occupying the No. 5 spot for the best graduate business program.</p>
<p>This year, <em>U.S. News</em> also ranked the nation’s top PhD programs in the sciences, which it last evaluated in 2014. The magazine awarded No. 1 spots to MIT programs in biology (tied with Stanford University and the University of California at Berkeley), computer science (tied with Carnegie Mellon University, Stanford, and Berkeley), and physics (tied with Stanford). No. 2 spots went to MIT programs in chemistry (tied with Harvard University, Stanford, and Berkeley), earth sciences (tied with Stanford and Berkeley); and mathematics (tied with Harvard, Stanford, and Berkeley).</p>
<p>Among individual engineering disciplines, MIT placed first in six areas: aerospace/aeronautical/astronautical engineering (tied with Caltech), chemical engineering, computer engineering, electrical/electronic/communications engineering (tied with Stanford and Berkeley), materials engineering, and mechanical engineering. It placed second in nuclear engineering.</p>
<p>In the rankings of individual MBA specialties, MIT placed first in information systems and production/operations. It placed second in supply chain/logistics and third in entrepreneurship.</p>
<p><em>U.S. News</em> does not issue annual rankings for all doctoral programs but revisits many every few years. This year, MIT ranked in the top five for 24 of the 37 science disciplines evaluated.</p>
<p>The magazine bases its rankings of graduate schools of engineering and business on two types of data: reputational surveys of deans and other academic officials, and statistical indicators that measure the quality of a school’s faculty, research, and students. The magazine’s less-frequent rankings of programs in the sciences, social sciences, and humanities are based solely on reputational surveys.</p>
Photo: AboveSummit with Christopher HartingRankings, School of Science, School of Engineering, Sloan School of Management, Business and management, Graduate, postdoctoral, education, Education, teaching, academics, Aeronautical and astronautical engineering, Chemical engineering, DMSE, Electrical Engineering & Computer Science (eecs), Materials Science and Engineering, Mechanical engineering, Nuclear science and engineering, Biology, Chemistry, Physics, Mathematics, EAPS, Earth and atmospheric sciencesPhysicists discover new quantum electronic material http://news.mit.edu/2018/physicists-discover-new-quantum-electronic-material-0319
With an atomic structure resembling a Japanese basketweaving pattern, “kagome metal” exhibits exotic, quantum behavior.Mon, 19 Mar 2018 12:00:46 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/physicists-discover-new-quantum-electronic-material-0319<p>A motif of Japanese basketweaving known as the kagome pattern has preoccupied physicists for decades. Kagome baskets are typically made from strips of bamboo woven into a highly symmetrical pattern of interlaced, corner-sharing triangles.</p>
<p>If a metal or other conductive material could be made to resemble such a kagome pattern at the atomic scale, with individual atoms arranged in similar triangular patterns, it should in theory exhibit exotic electronic properties.&nbsp;</p>
<p>In a paper published today in <em>Nature</em>, physicists from MIT, Harvard University, and Lawrence Berkeley National Laboratory report that they have for the first time produced a kagome metal — an electrically conducting crystal, made from layers of iron and tin atoms, with each atomic layer arranged in the repeating pattern of a kagome lattice.</p>
<p>When they flowed a current across the kagome layers within the crystal, the researchers observed that the triangular arrangement of atoms induced strange, quantum-like behaviors in the passing current. Instead of flowing straight through the lattice, electrons instead veered, or bent back within the lattice.</p>
<p>This behavior is a three-dimensional cousin of the so-called Quantum Hall effect, in which electrons flowing through a two-dimensional material will exhibit a “chiral, topological state,” in which they bend into tight, circular paths and flow along edges without losing energy.</p>
<p>“By constructing the kagome network of iron, which is inherently magnetic, this exotic behavior persists to room temperature and higher,” says Joseph Checkelsky, assistant professor of physics at MIT. “The charges in the crystal feel not only the magnetic fields from these atoms, but also a purely quantum-mechanical magnetic force from the lattice. This could lead to perfect conduction, akin to superconductivity, in future generations of materials.”</p>
<p>To explore these findings, the team measured the energy spectrum within the crystal, using a modern version of an effect first discovered by Heinrich Hertz and explained by Einstein, known as the photoelectric effect.&nbsp;</p>
<p>“Fundamentally, the electrons are first ejected from the material’s surface and are then detected as a function of takeoff angle and kinetic energy,” says Riccardo Comin, an assistant professor of physics at MIT. “The resulting images are a very direct snapshot of the electronic levels occupied by electrons, and in this case they revealed the creation of nearly massless ‘Dirac’ particles, an electrically charged version of photons, the quanta of light.”</p>
<p>The spectra revealed that electrons flow through the crystal in a way that suggests the originally massless electrons gained a relativistic mass, similar to particles known as massive Dirac fermions. Theoretically, this is explained by the presence of the lattice’s constituent iron and tin atoms. The former are magnetic and give rise to a “handedness,” or chirality. The latter possess a heavier nuclear charge, producing a large local electric field. As an external current flows by, it senses the tin’s field not as an electric field but as a magnetic one, and bends away.</p>
<p>The research team was led by Checkelsky and Comin, as well as graduate students Linda Ye and Min Gu Kang in collaboration with Liang Fu, the Biedenharn Associate Professor of Physics, and postdoc Junwei Liu. The team also includes Christina Wicker ’17, research scientist Takehito Suzuki of MIT, Felix von Cube and David Bell of Harvard, and Chris Jozwiak, Aaron Bostwick, and Eli Rotenberg of Lawrence Berkeley National Laboratory.</p>
<p><strong>“No alchemy required”</strong></p>
<p>Physicists have theorized for decades that electronic materials could support exotic Quantum Hall behavior with their inherent magnetic character and lattice geometry. It wasn’t until several years ago that researchers made progress in realizing such materials.</p>
<p>“The community realized, why not make the system out of something magnetic, and then the system’s inherent magnetism could perhaps drive this behavior,” says Checkelsky, who at the time was working as a researcher at the University of Tokyo.&nbsp;</p>
<p>This eliminated the need for laboratory produced fields, typically 1 million times as strong as the Earth’s magnetic field, needed to observe this behavior.&nbsp;</p>
<p>“Several research groups were able to induce a Quantum Hall effect this way, but still at ultracold temperatures a few degrees above absolute zero — the result of shoehorning magnetism into a material where it did not naturally occur,” Checkelsky says.&nbsp;</p>
<p>At MIT, Checkelsky has instead looked for ways to drive this behavior with “instrinsic magnetism.” A key insight, motivated by the doctoral work of Evelyn Tang PhD ’15 and Professor Xiao-Gang Wen, was to seek this behavior in the kagome lattice. To do so, first author Ye ground together iron and tin, then heated the resulting powder in a furnace, producing crystals at about 750 degrees Celsius — the temperature at which iron and tin atoms prefer to arrange in a kagome-like pattern. She then submerged the crystals in an ice bath to enable the lattice patterns to remain stable at room temperature.</p>
<p>“The kagome pattern has big empty spaces that might be easy to weave by hand, but are often unstable in crystalline solids which prefer the best packing of atoms,” Ye says. “The trick here was to fill these voids with a second type of atom in a structure that was at least stable at high temperatures. Realizing these quantum materials doesn’t need alchemy, but instead materials science and patience.”</p>
<p><strong>Bending and skipping toward zero-energy loss</strong></p>
<p>Once the researchers grew several samples of crystals, each about a millimeter wide, they handed the samples off to collaborators at Harvard, who imaged the individual atomic layers within each crystal using transmission electron microscopy. The resulting images revealed that the arrangement of iron and tin atoms within each layer resembled the triangular patterns of the kagome lattice. Specifically, iron atoms were positioned at the corners of each triangle, while a single tin atom sat within the larger hexagonal space created between the interlacing triangles.</p>
<p>Ye then ran an electric current through the crystalline layers and monitored their flow via electrical voltages they produced. She found that the charges deflected in a manner that seemed two-dimensional, despite the three-dimensional nature of the crystals. The definitive proof came from the photoelectron experiments conducted by co-first author Kang who, in concert with the LBNL team, was able to show that the electronic spectra corresponded to effectively two-dimensional electrons.&nbsp;</p>
<p>“As we looked closely at the electronic bands, we noticed something unusual,” Kang adds. “The electrons in this magnetic material behaved as massive Dirac particles, something that had been predicted long ago but never been seen before in these systems.”</p>
<p>“The unique ability of this material to intertwine magnetism and topology suggests that they may well engender other emergent phenomena,” Comin says. “Our next goal is to detect and manipulate the edge states which are the very consequence of the topological nature of these newly discovered quantum electronic phases.”&nbsp;</p>
<p>Looking further, the team is now investigating ways to stabilize other more highly two-dimensional kagome lattice structures. Such materials, if they can be synthesized, could be used to explore not only devices with zero energy loss, such as dissipationless power lines, but also applications toward quantum computing.</p>
<p>“For new directions in quantum information science there is a growing interest in novel quantum circuits with pathways that are dissipationless and chiral,” Checkelsky says. “These kagome metals offer a new materials design pathway to realizing such new platforms for quantum circuitry.”</p>
<p>This research was supported in part by the Gordon and Betty Moore Foundation and the National Science Foundation.</p>
An illustration depicting a kagome metal — an electrically conducting crystal, made from layers of iron and tin atoms, with each atomic layer arranged in the repeating pattern of a kagome lattice. Images by Felice Frankel; Illustration overlays by Chelsea TurnerEnergy, Materials Research Laboratory, Materials Science and Engineering, Physics, Quantum computing, Research, School of ScienceScientists detect radio echoes of a black hole feeding on a starhttp://news.mit.edu/2018/scientists-detect-radio-echoes-black-hole-feeding-star-0319
Signals suggest black hole emits a jet of energy proportional to the stellar material it gobbles up.Sun, 18 Mar 2018 23:59:59 -0400Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/scientists-detect-radio-echoes-black-hole-feeding-star-0319<p>On Nov. 11, 2014, a global network of telescopes picked up signals from 300 million light years away that were created by a tidal disruption flare — an explosion of electromagnetic energy that occurs when a black hole rips apart a passing star. Since this discovery, astronomers have trained other telescopes on this very rare event to learn more about how black holes devour matter and regulate the growth of galaxies.</p>
<p>Scientists from MIT and Johns Hopkins University have now detected radio signals from the event that match very closely with X-ray emissions produced from the same flare 13 days earlier. They believe these radio “echoes,” which are more than 90 percent similar to the event’s X-ray emissions, are more than a passing coincidence. Instead, they appear to be evidence of a giant jet of highly energetic particles streaming out from the black hole as stellar material is falling in.</p>
<p>Dheeraj Pasham, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research, says the highly similar patterns suggest that the power of the jet shooting out from the black hole is somehow controlled by the rate at which the black hole is feeding on the obliterated star.</p>
<p>“This is telling us the black hole feeding rate is controlling the strength of the jet it produces,” Pasham says. “A well-fed black hole produces a strong jet, while a malnourished black hole produces a weak jet or no jet at all. This is the first time we’ve seen a jet that’s controlled by a feeding supermassive black hole.”</p>
<p>Pasham says scientists have suspected that black hole jets are powered by their accretion rate, but they have never been able to observe this relationship from a single event.</p>
<p>“You can do this only with these special events where the black hole is just sitting there doing nothing, and then suddenly along comes a star, giving it a lot of fuel to power itself,” Pasham says. “That’s the perfect opportunity to study such things from scratch, essentially.”</p>
<p>Pasham and his collaborator, Sjoert van Velzen of Johns Hopkins University, report their results in a paper published this week in the <em>Astrophysical Journal.</em></p>
<p><strong>Up for debate</strong></p>
<p>Based on theoretical models of black hole evolution, combined with observations of distant galaxies, scientists have a general understanding for what transpires during a tidal disruption event: As a star passes close to a black hole, the black hole’s gravitational pull generates tidal forces on the star, similar to the way in which the moon stirs up tides on Earth.</p>
<p>However, a black hole’s gravitational forces are so immense that they can disrupt the star, stretching and flattening it like a pancake and eventually shredding the star to pieces. In the aftermath, a shower of stellar debris rains down and gets caught up in an accretion disk — a swirl of cosmic material that eventually funnels into and feeds the black hole.</p>
<p>This entire process generates colossal bursts of energy across the electromagnetic spectrum. Scientists have observed these bursts in the optical, ultraviolet, and X-ray bands, and also occasionally in the radio end of the spectrum. The source of the X-ray emissions is thought to be ultrahot material in the innermost regions of the accretion disk, which is just about to fall into the black hole. Optical and ultraviolet emissions likely arise from material further out in the disk, which will eventually be pulled into the black hole.</p>
<p>However, what gives rise to radio emissions during a tidal disruption flare has been up for debate.</p>
<p>“We know that the radio waves are coming from really energetic electrons that are moving in a magnetic field — that is a well-established process,” Pasham says. “The debate has been, where are these really energetic electrons coming from?”</p>
<p>Some scientists propose that, in the moments after the stellar explosion, a shockwave propagates outward and energizes the plasma particles in the surrounding medium, in a process that in turn emits radio waves. In such a scenario, the pattern of emitted radio waves would look radically different from the pattern of X-rays produced from infalling stellar debris.</p>
<p>“What we found basically challenges this paradigm,” Pasham says.</p>
<p><strong>A shifting pattern</strong></p>
<p>Pasham and van Velzen looked through data recorded from a tidal disruption flare discovered in 2014 by the global telescope network ASASSN (All-sky Automated Survey for Supernovae). Soon after the initial discovery, multiple electromagnetic telescopes focused on the event, which astronomers coined ASASSN-14li. Pasham and van Velzen perused radio data from three telescopes of the event over 180 days.</p>
<p>The researchers looked through the compiled radio data and discovered a clear resemblance to patterns they had previously observed in X-ray data from the same event. When they fit the radio data over the X-ray data, and shifted the two around to compare their similarities, they found the datasets were most similar, with a 90 percent resemblance, when shifted by 13 days. That is, the same fluctuations in the X-ray spectrum appeared 13 days later in the radio band.</p>
<p>“The only way that coupling can happen is if there is a physical process that is somehow connecting the X-ray-producing accretion flow with the radio-producing region,” Pasham says.</p>
<p>From this same data, Pasham and van Velzen calculated the size of the X-ray-emitting region to be about 25 times the size of the sun, while the radio-emitting region was about 400,000 times the solar radius.</p>
<p>“It’s not a coincidence that this is happening,” Pasham says. “Clearly there’s a causal connection between this small region producing X-rays, and this big region producing radio waves.”</p>
<p>The team proposes that the radio waves were produced by a jet of high-energy particles that began to stream out from the black hole shortly after the black hole began absorbing material from the exploded star. Because the region of the jet where these radio waves first formed was incredibly dense (tightly packed with electrons), a majority of the radio waves were immediately absorbed by other electrons.</p>
<p>It was only when electrons traveled downstream of the jet&nbsp;that the radio waves could escape — producing the signal that the researchers eventually detected. Thus, they say, the strength of the jet must be controlled by the accretion rate, or the speed at which the black hole is consuming X-ray-emitting stellar debris.</p>
<p>Ultimately, the results may help scientists better characterize the physics of jet behavior — an essential ingredient in modeling the evolution of galaxies. It’s thought that galaxies grow by producing new stars, a process that requires very cold temperatures. When a black hole emits a jet of particles, it essentially heats up the surrounding galaxy, putting a temporary stop on stellar production. Pasham says the team’s new insights into jet production and black hole accretion may help to simplify models of galaxy evolution.</p>
<p>“If the rate at which the black hole is feeding is proportional to the rate at which it’s pumping out energy, and if that really works for every black hole, it’s a simple prescription you can use in simulations of galaxy evolution,” Pasham says. “So this is hinting toward some bigger picture.”</p>
Artist's impression of an inner accretion flow and a jet from a supermassive black hole when it is actively feeding, for example, from a star that it recent tore apart.Image: ESO/L. CalçadaAstronomy, Astrophysics, Black holes, Kavli Institute, Physics, Research, School of Science, Space, astronomy and planetary scienceA new era in fusion research at MIThttp://news.mit.edu/2018/new-era-fusion-research-mit-eni-0309
MIT Energy Initiative founding member Eni announces support for key research through MIT Laboratory for Innovation in Fusion Technologies.Fri, 09 Mar 2018 00:00:00 -0500Francesca McCaffrey | MIT Energy Initiativehttp://news.mit.edu/2018/new-era-fusion-research-mit-eni-0309<p>A new chapter is beginning for fusion energy research at MIT.</p>
<p>This week the Italian energy company Eni, a founding member of the MIT Energy Initiative (MITEI), announced it has reached an agreement with MIT to fund fusion research projects run out of the MIT Plasma Science and Fusion Center (PSFC)’s newly created Laboratory for Innovation in Fusion Technologies (LIFT). The expected investment in these research projects will amount to about $2 million over the following years.</p>
<p>This is part of a <a href="http://news.mit.edu/2018/mit-newly-formed-company-launch-novel-approach-fusion-power-0309">broader engagement </a>with fusion research and the Institute as a whole: Eni also announced a commitment of $50 million to a new private company with roots at MIT, Commonwealth Fusion Systems (CFS), which aims to make affordable, scalable <a href="http://news.mit.edu/2018/3q-zach-hartwig-mit-big-push-fusion-0309">fusion power a reality</a>.</p>
<p>“This support of LIFT is a continuation of Eni’s commitment to meeting growing global energy demand while tackling the challenge of climate change through its research portfolio at MIT,” says Robert C. Armstrong, MITEI’s director and the Chevron Professor of Chemical Engineering at MIT. “Fusion is unique in that it is a zero-carbon, dispatchable, baseload technology, with a limitless supply of fuel, no risk of runaway reaction, and no generation of long-term waste. It also produces thermal energy, so it can be used for heat as well as power.”</p>
<p>Still, there is much more to do along the way to perfecting the design and economics of compact fusion power plants. Eni will fund research projects at LIFT that are a continuation of this research and focus on fusion-specific solutions. “We are thrilled at PSFC to have these projects funded by Eni, who has made a clear commitment to developing fusion energy,” says Dennis Whyte, the director of PSFC and the Hitachi America Professor of Engineering at MIT. “LIFT will focus on cutting-edge technology advancements for fusion, and will significantly engage our MIT students who are so adept at innovation.”</p>
<p><strong>Tackling fusion’s challenges</strong></p>
<p>The inside of a fusion device is an extreme environment. The creation of fusion energy requires the smashing together of light elements, such as hydrogen, to form heavier elements such as helium, a process that releases immense amounts of energy. The temperature at which this process takes place is too hot for solid materials, necessitating the use of magnets to hold the hot plasma in place.</p>
<p>One of the projects PSFC and Eni intend to carry out will study the effects of high magnetic fields on molten salt fluid dynamics. One of the key elements of the fusion pilot plant currently being studied at LIFT is the liquid immersion blanket, essentially a flowing pool of molten salt that completely surrounds the fusion energy core. The purpose of this blanket is threefold: to convert the kinetic energy of fusion neutrons to heat for eventual electricity production; to produce tritium — a main component of the fusion fuel; and to prevent the neutrons from reaching other parts of the machine and causing material damage.</p>
<p>It’s critical for researchers to be able to predict how the molten salt in such an immersion blanket would move when subjected to high magnetic fields such as those found within a fusion plant. As such, the researchers and their respective teams plan to study the effects of these magnetohydrodynamic forces on the salt’s fluid dynamics.</p>
<p><strong>A history of innovation</strong></p>
<p>During the 23 years MIT’s Alcator C-Mod tokamak fusion experiment was in operation, it repeatedly advanced records for plasma pressure in a magnetic confinement device. Its compact, high-magnetic-field fusion design confined superheated plasma in a small donut-shaped chamber.</p>
<p>“The key to this success was the innovations pursued more than 20 years ago at PSFC in developing copper magnets that could access fields well in excess of other fusion experiments. The coupling between innovative technology development and advancing fusion science is in the DNA of the Plasma Science and Fusion Center,” says PSFC Deputy Director Martin Greenwald.</p>
<p>In its final run in 2016, Alcator C-Mod set a new world record for plasma pressure, the key ingredient to producing net energy from fusion. Since then, PSFC researchers have used data from these decades of C-Mod experiments to continue to advance fusion research. Just last year, they used C-Mod data to create a new method of heating fusion plasmas in tokamaks which could result in the heating of ions to energies an order of magnitude greater than previously reached.</p>
<p><strong>A commitment to low-carbon energy</strong></p>
<p>MITEI’s mission is to advance low-carbon and no-carbon emissions solutions to efficiently meet growing global energy needs. Critical to this mission are collaborations between academia, industry, and government — connections MITEI helps to develop in its role as MIT’s hub for multidisciplinary energy research, education, and outreach.</p>
<p>Eni is an inaugural, founding member of the MIT Energy Initiative, and it was through their engagement with MITEI that they became aware of the fusion technology commercialization being pursued by CFS and its immense potential for revolutionizing the energy system. It was through these discussions, as well, that Eni investors learned of the high-potential fusion research projects taking place through LIFT at MIT, spurring them to support the future of fusion at the Institute itself.</p>
<p>Eni CEO Claudio Descalzi said, “Today is a very important day for us. Thanks to this agreement, Eni takes a significant step forward toward the development of alternative energy sources with an ever lower environmental impact. Fusion is the true energy source of the future, as it is completely sustainable, does not release emissions or waste, and is potentially inexhaustible. It is a goal that we are determined to reach quickly.”<em>&nbsp;</em>He added, “We are pleased and excited to pursue such a challenging goal with a collaborator like MIT, with unparalleled experience in the field and a long-standing and fruitful alliance with Eni.”</p>
<p>These fusion projects are the latest in a line of MIT-Eni collaborations on low- and no-carbon energy projects. One of the earliest of these was the Eni-MIT Solar Frontiers Center, established in 2010 at MIT. Through its mission to develop competitive solar technologies, the center’s research has yielded the thinnest, lightest solar cells ever produced, effectively able to turn any surface, from fabric to paper, into a functioning solar cell. The researchers at the center have also developed new, luminescent materials that could allow windows to efficiently collect solar power.</p>
<p>Other fruits of MIT-Eni collaborations include research into carbon capture systems to be installed in cars, wearable technologies to improve workplace safety, energy storage, and the conversion of carbon dioxide into fuel.</p>
MIT Energy Initiative, Energy, Alternative energy, Renewable energy, Collaboration, Nuclear power and reactors, Nuclear science and engineering, Fusion, Plasma Science and Fusion Center, Research, School of Engineering, Physics, Industry3Q: Zach Hartwig on MIT&#039;s big push on fusionhttp://news.mit.edu/2018/3q-zach-hartwig-mit-big-push-fusion-0309
Researchers will work with industrial collaborators to pursue fusion as a source of carbon-free power.Fri, 09 Mar 2018 00:00:00 -0500MIT News Officehttp://news.mit.edu/2018/3q-zach-hartwig-mit-big-push-fusion-0309<p><em>Today, MIT <a href="http://news.mit.edu/2018/mit-newly-formed-company-launch-novel-approach-fusion-power-0309">announced plans</a> to work with a newly formed company, Commonwealth Fusion Systems (CFS), to realize the promise of fusion as a source of unlimited, safe, carbon-free energy. Zach Hartwig, an assistant professor of nuclear science and engineering, is one of the Institute’s leads on the effort, along with others in MIT’s Plasma Fusion and Science Center (PSFC). He spoke with </em>MIT News<em> about the group’s vision for a fusion-powered future.</em></p>
<p><strong>Q: </strong>Why is this new collaboration needed to support fusion energy?</p>
<p><strong>A:</strong> Mitigating global climate change requires new sources of zero-carbon energy as soon as we can deliver them, and we are going to need a completely new approach to ensure that fusion energy can be a significant part of the solution.</p>
<p>The hard reality of climate change is that every single nation that has ever industrialized and made a better life for its citizens did so at the expense of the climate. There is, at present, simply no other way to do this than to dump carbon dioxide into the atmosphere by burning fossil fuels for energy.</p>
<p>As a global society, we have to do better. Fusion energy represents one tremendously attractive pathway, if we can demonstrate its potential and accelerate its commercial deployment. This is going to require new models of innovation that couple research institutions, such as MIT, with private companies, such as CFS, that are capable of commercializing fusion — and then providing that relationship with sustainable, patient capital that can fund the development of breakthrough energy solutions at scale.</p>
<p>Fusion is the fundamental energy source of the universe, powering our sun and the distant stars. The promise of harnessing fusion to produce energy on Earth is simple: limitless, safe, zero-carbon energy.</p>
<p>Like the governments of many nations, the U.S. has funded basic research on fusion science and technology since the 1950s, making tremendous progress toward the goal of fusion energy. MIT has long been a leading institution in fusion research, receiving research support primarily from the Department of Energy, including the funding of three major fusion energy experiments at MIT culminating in the Alcator C-Mod tokamak, which ended 25 years of operation in 2016. The DOE continues its support of fusion energy research at other facilities around the U.S. and the world, including the ITER experiment now under construction in France.</p>
<p>However, the mission and structure of federal research sponsorship does not extend to commercialization of the basic research it funds; this is the role of private companies, which are structured to raise capital and efficiently deploy competitive technologies into the commercial marketplace. But this raises a crucial question: How does promising, federally funded research transition into a robust commercial product — particularly in fusion energy, where the timelines and financial costs are higher than in many other technologies?</p>
<p>We believe that this new model of collaboration between MIT and CFS provides this bridge. MIT continues its involvement beyond the federally funded research stage, providing scientific expertise and infrastructure for research, while CFS provides stable funding from long-term investment and a mechanism to accelerate and commercialize the technology.</p>
<p>Importantly, this model is not limited to fusion energy, but creates a new framework for research universities and energy companies to partner on large-scale, long-term energy projects.</p>
<p>A critical, relatively recent technology breakthrough plays an important enabling role in this collaboration: a class of materials known as high-temperature superconductors that have only become commercially available with sufficient performance and quantity for fusion application within the last five years or so.</p>
<p>These materials will enable MIT and CFS to substantially increase the performance of superconducting fusion magnets, the principal initial focus of the research collaboration. These magnets will lead to dramatically smaller, lower-cost fusion devices that can produce net energy up to several hundred megawatts of power, and, most importantly, be strongly competitive in the energy marketplace in less than 20 years.</p>
<p><strong>Q: </strong>What is Commonwealth Fusion Systems? Is it related to MIT?</p>
<p><strong>A:</strong> Commonwealth Fusion Systems (CFS) is an independent, for-profit company created by former MIT staff and students to help accelerate the commercialization of fusion energy. CFS will sponsor research at MIT and work closely with us to determine and execute the research program leading to an experiment we call SPARC. We anticipate that this relationship will be an ongoing and long-term one.</p>
<p>CFS has raised significant funding to support efforts at MIT to achieve fusion energy and to conduct related business activities. The first part of these <a href="http://news.mit.edu/2018/new-era-fusion-research-mit-eni-0309">investments come from Eni</a>, a multinational energy company seeking to diversify its portfolio with a forward-looking investment in fusion energy.</p>
<p>Some of this funding will come to PSFC and others at MIT, to support our research; some of it will go to support CFS’s own R&amp;D; and some may go to other institutions with relevant expertise. As with other sponsored research on campus, the results of MIT’s research will be publishable, and the Institute will own and license the intellectual property rights to discoveries made by its scientists along the way. The funding will also support MIT’s educational mission, providing research opportunities for graduate students.</p>
<p><strong>Q: </strong>How does this effort differ from other ongoing approaches to fusion energy?</p>
<p><strong>A: </strong>Fusion energy is widely recognized as having enormous potential. It is, therefore, pursued by a variety of players in a variety of ways.</p>
<p>One can broadly classify these efforts into two categories: government-funded research in magnetic confinement fusion, focusing primarily on the tokamak concept with the international ITER project as its focal point; and privately funded companies pursuing primarily non-tokamak-based devices. These two approaches are different from each other in their funding sources, organizational structures, mission objectives, and risk management philosophies.</p>
<p>The government-funded tokamak approach to fusion via ITER is a massive long-term effort supported by the governments of six nations — China, India, Japan, Russia, South Korea, and the United States — and the European Union. Being built in the south of France, ITER is a fusion science experiment designed to produce net fusion power sometime after 2035, if the present schedule holds.</p>
<p>ITER leverages proven physics built on 50 years of successful government-backed research, mitigating a critical risk in the underlying science. On the other hand, its sheer scale requires very high costs, international organizational challenges and, ultimately, long timelines that put fusion power on the grid sometime after 2060, quite possibly too late to substantially mitigate global warming associated with combustion of fossil fuels.</p>
<p>In contrast, the private fusion companies are smaller, nimbler, and learn by iterating quickly. This approach, coupled with private funding, provides driving pressure to move as quickly and efficiently as possible to commercialize fusion. Their universal challenge, however, is that their fusion concepts are based on unproven physics that, at best, may require a long time and extensive resources to prove the science and, at worst, may be unable to scale to the performance required for a fusion power plant.</p>
<p>The high-field pathway to fusion energy proposed by MIT and CFS seeks to take the best of both approaches — coupling the proven physics of the tokamak with the drive of a company focused on commercialization — and isolating the majority of the technical risk in the engineering development of the high-field magnets.</p>
<p>Overall, we believe two things about all of the ongoing efforts on fusion energy, both government- and privately funded. First, fusion energy is too important to solving major challenges facing humanity to focus exclusively on a single approach, particularly where parallel technology and funding pathways can exist side by side: There’s value in carefully incorporating a diversity of approaches to fusion energy in order to benefit from the different risk and reward trade-offs embodied in each. Second, all of the approaches are part of a nascent but growing fusion ecosystem that can work together in a surprising number of areas to achieve our mutual goal of fusion energy in time to make a difference.</p>
Zach HartwigPhoto: Bryce VickmarkFusion, Nuclear science and engineering, School of Engineering, Plasma Science and Fusion Center, Alternative energy, Renewable energy, Energy, 3 Questions, Industry, Physics, Nuclear power and reactorsMIT and newly formed company launch novel approach to fusion powerhttp://news.mit.edu/2018/mit-newly-formed-company-launch-novel-approach-fusion-power-0309
Goal is for research to produce a working pilot plant within 15 years.Fri, 09 Mar 2018 00:00:00 -0500David Chandler | MIT News Officehttp://news.mit.edu/2018/mit-newly-formed-company-launch-novel-approach-fusion-power-0309<p>Progress toward the long-sought dream of fusion power — potentially an inexhaustible and zero-carbon source of energy — could be about to take a dramatic leap forward.</p>
<p>Development of this carbon-free, combustion-free source of energy is now on a faster track toward realization, thanks to a <a href="http://news.mit.edu/2018/3q-zach-hartwig-mit-big-push-fusion-0309">collaboration between MIT and a new private company</a>, Commonwealth Fusion Systems. CFS will join with MIT to carry out rapid, staged research leading to a new generation of fusion experiments and power plants based on advances in high-temperature superconductors — work made possible by decades of federal government funding for basic research.</p>
<p>CFS is announcing today that it has attracted an investment of $50 million in support of this effort from the Italian energy company Eni. In addition, CFS continues to seek the support of additional investors. CFS will fund fusion research at MIT as part of this collaboration, with an ultimate goal of rapidly commercializing fusion energy and establishing a new industry.</p>
<p>“This is an important historical moment: Advances in superconducting magnets have put fusion energy potentially within reach, offering the prospect of a safe, carbon-free energy future,” says MIT President L. Rafael Reif. “As humanity confronts the rising risks of climate disruption, I am thrilled that MIT is joining with industrial allies, both longstanding and new, to run full-speed toward this transformative vision for our shared future on Earth.”</p>
<p>“Everyone agrees on the eventual impact and the commercial potential of fusion power, but then the question is: How do you get there?” adds Commonwealth Fusion Systems CEO Robert Mumgaard SM ’15, PhD ’15. “We get there by leveraging the science that’s already developed, collaborating with the right partners, and tackling the problems step by step.”</p>
<p>MIT Vice President for Research Maria Zuber, who has written <a href="https://www.bostonglobe.com/opinion/2018/03/09/new-approach-fusion-energy-starts-today/cc7kpF93xLaopO5xdobKIO/story.html">an op-ed on the importance of this news</a> that appears in today’s <em>Boston Globe</em>, notes that MIT’s collaboration with CFS required concerted effort among people and offices at MIT that support innovation:&nbsp;“We are grateful for the MIT team that worked tirelessly to form this collaboration. Associate Provost Karen Gleason’s leadership was instrumental — as was the creativity, diligence, and care of the Office of the General Counsel, the Office of Sponsored Programs, the Technology Licensing Office, and the MIT Energy Initiative. A great job by all.”</p>
<p><strong>Superconducting magnets are key</strong></p>
<p>Fusion, the process that powers the sun and stars, involves light elements, such as hydrogen, smashing together to form heavier elements, such as helium — releasing prodigious amounts of energy in the process. This process produces net energy only at extreme temperatures of hundreds of millions of degrees Celsius, too hot for any solid material to withstand. To get around that, fusion researchers use magnetic fields to hold in place the hot plasma — a kind of gaseous soup of subatomic particles — keeping it from coming into contact with any part of the donut-shaped chamber.</p>
<p>The new effort aims to build a compact device capable of generating 100 million watts, or 100 megawatts (MW), of fusion power. This device will, if all goes according to plan, demonstrate key technical milestones needed to ultimately achieve a full-scale prototype of a fusion power plant that could set the world on a path to low-carbon energy. If widely disseminated, such fusion power plants could meet a substantial fraction of the world’s growing energy needs while drastically curbing the greenhouse gas emissions that are causing global climate change.</p>
<p>“Today is a very important day for us,” says Eni CEO Claudio Descalzi. “Thanks to this agreement, Eni takes a significant step forward toward the development of alternative energy sources with an ever-lower environmental impact. Fusion is the true energy source of the future, as it is completely sustainable, does not release emissions or long-term waste, and is potentially inexhaustible. It is a goal that we are increasingly determined to reach quickly.”</p>
<p>CFS will support more than $30 million of MIT research over the next three years through investments by Eni and others. This work will aim to develop the world’s most powerful large-bore superconducting electromagnets — the key component that will enable construction of a much more compact version of a fusion device called a tokamak. The magnets, based on a superconducting material that has only recently become available commercially, will produce a magnetic field four times as strong as that employed in any existing fusion experiment, enabling a more than tenfold increase in the power produced by a tokamak of a given size.</p>
<p><strong>Conceived at PSFC</strong></p>
<p>The project was conceived by researchers from MIT’s Plasma Science and Fusion Center, led by PSFC Director Dennis Whyte, Deputy Director Martin Greenwald, and a team that grew to include representatives from across MIT, involving disciplines from engineering to physics to architecture to economics. The core PSFC team included Mumgaard, Dan Brunner PhD ’13, and Brandon Sorbom PhD ’17 —&nbsp;all now leading CFS — as well as Zach Hartwig PhD ’14, now an assistant professor of nuclear science and engineering at MIT.</p>
<p>Once the superconducting electromagnets are developed by researchers at MIT and CFS — expected to occur within three years — MIT and CFS will design and build a compact and powerful fusion experiment, called SPARC, using those magnets. The experiment will be used for what is expected to be a final round of research enabling design of the world’s first commercial power-producing fusion plants.</p>
<p>SPARC is designed to produce about 100 MW of heat. While it will not turn that heat into electricity, it will produce, in pulses of about 10 seconds, as much power as is used by a small city. That output would be more than twice the power used to heat the plasma, achieving the ultimate technical milestone: positive net energy from fusion.</p>
<p>This demonstration would establish that a new power plant of about twice SPARC’s diameter, capable of producing commercially viable net power output, could go ahead toward final design and construction. Such a plant would become the world’s first true fusion power plant, with a capacity of 200 MW of electricity, comparable to that of most modern commercial electric power plants. At that point, its implementation could proceed rapidly and with little risk, and such power plants could be demonstrated within 15 years, say Whyte, Greenwald, and Hartwig.</p>
<p><strong>Complementary to ITER</strong></p>
<p>The project is expected to complement the research planned for a large international collaboration called ITER, currently under construction as the world’s largest fusion experiment at a site in southern France. If successful, ITER is expected to begin producing fusion energy around 2035.</p>
<p>“Fusion is way too important for only one track,” says Greenwald, who is a senior research scientist at PSFC.</p>
<p>By using magnets made from the newly available superconducting material — a steel tape coated with a compound called yttrium-barium-copper oxide (YBCO) — SPARC is designed to produce a fusion power output about a fifth that of ITER, but in a device that is only about 1/65 the volume, Hartwig says. The ultimate benefit of the YBCO tape, he adds, is that it drastically reduces the cost, timeline, and organizational complexity required to build net fusion energy devices, enabling new players and new approaches to fusion energy at university and private company scale. &nbsp;</p>
<p>The way these high-field magnets slash the size of plants needed to achieve a given level of power has repercussions that reverberate through every aspect of the design. Components that would otherwise be so large that they would have to be manufactured on-site could instead be factory-built and trucked in; ancillary systems for cooling and other functions would all be scaled back proportionately; and the total cost and time for design and construction would be drastically reduced.</p>
<p>“What you’re looking for is power production technologies that are going to play nicely within the mix that’s going to be integrated on the grid in 10 to 20 years,” Hartwig says. “The grid right now is moving away from these two- or three-gigawatt monolithic coal or fission power plants. The range of a large fraction of power production facilities in the U.S. is now is in the 100 to 500 megawatt range. Your technology has to be amenable with what sells to compete robustly in a brutal marketplace.”</p>
<p>Because the magnets are the key technology for the new fusion reactor, and because their development carries the greatest uncertainties, Whyte explains, work on the magnets will be the initial three-year phase of the project — building upon the strong foundation of federally funded research conducted at MIT and elsewhere. Once the magnet technology is proven, the next step of designing the SPARC tokamak is based on a relatively straightforward evolution from existing tokamak experiments, he says.</p>
<p>“By putting the magnet development up front,” says Whyte, the Hitachi America Professor of Engineering and head of MIT’s Department of Nuclear Science and Engineering, “we think that this gives you a really solid answer in three years, and gives you a great amount of confidence moving forward that you’re giving yourself the best possible chance of answering the key question, which is: Can you make net energy from a magnetically confined plasma?”</p>
<p>The research project aims to leverage the scientific knowledge and expertise built up over decades of government-funded research — including MIT’s work, from 1971 to 2016, with its Alcator C-Mod experiment, as well as its predecessors — in combination with the intensity of a well-funded startup company. Whyte, Greenwald, and Hartwig say that this approach could greatly shorten the time to bring fusion technology to the marketplace — while there’s still time for fusion to make a real difference in climate change.</p>
<p><strong>MITEI participation</strong></p>
<p>Commonwealth Fusion Systems is a private company and will join the <a href="http://energy.mit.edu/">MIT Energy Initiative</a> (MITEI) as part of a new university-industry partnership built to carry out this plan. The collaboration between MITEI and CFS is expected to bolster MIT research and teaching on the science of fusion, while at the same time building a strong industrial partner that ultimately could be positioned to bring fusion power to real-world use.</p>
<p>“MITEI has created a new membership specifically for energy startups, and CFS is the first company to become a member through this new program,” says MITEI Director Robert Armstrong, the Chevron Professor of Chemical Engineering at MIT. “In addition to providing access to the significant resources and capabilities of the Institute, the membership is designed to expose startups to incumbent energy companies and their vast knowledge of the energy system. It was through their engagement with MITEI that Eni, one of MITEI’s founding members, became aware of SPARC’s tremendous potential for revolutionizing the energy system.”</p>
<p>Energy startups often require significant research funding to further their technology to the point where new clean energy solutions can be brought to market. Traditional forms of early-stage funding are often incompatible with the long lead times and capital intensity that are well-known to energy investors.</p>
<p>“Because of the nature of the conditions required to produce fusion reactions, you have to start at scale,” Greenwald says. “That’s why this kind of academic-industry collaboration was essential to enable the technology to move forward quickly. This is not like three engineers building a new app in a garage.”</p>
<p>Most of the initial round of funding from CFS will support collaborative research and development at MIT to demonstrate the new superconducting magnets.&nbsp; The team is confident that the magnets can be successfully developed to meet the needs of the task. Still, Greenwald adds, “that doesn’t mean it’s a trivial task,” and it will require substantial work by a large team of researchers. But, he points out, others have built magnets using this material, for other purposes, which had twice the magnetic field strength that will be required for this reactor. Though these high-field magnets were small, they do validate the basic feasibility of the concept.</p>
<p>In addition to its support of CFS, Eni has <a href="http://news.mit.edu/2018/new-era-fusion-research-mit-eni-0309">also announced an agreement</a> with MITEI to fund fusion research projects run out of PSFC’s Laboratory for Innovation in Fusion Technologies. The expected investment in these research projects amounts to about $2 million in the coming years.</p>
<p><strong>“Conservative physics”</strong></p>
<p>SPARC is an evolution of a tokamak design that has been studied and refined for decades. This included work at MIT that began in the 1970s, led by professors Bruno Coppi and Ron Parker, who developed the kind of high-magnetic-field fusion experiments that have been operated at MIT ever since, setting numerous fusion records.</p>
<p>“Our strategy is to use conservative physics, based on decades of work at MIT and elsewhere,” Greenwald says. “If SPARC does achieve its expected performance, my sense is that’s sort of a Kitty Hawk moment for fusion, by robustly demonstrating net power, in a device that scales to a real power plant.”</p>
Visualization of the proposed SPARC tokamak experiment. Using high-field magnets built with newly available high-temperature superconductors, this experiment would be the first controlled fusion plasma to produce net energy output.
Visualization by Ken Filar, PSFC research affiliateFusion, Nuclear science and engineering, School of Engineering, Plasma Science and Fusion Center, Alternative energy, Renewable energy, Energy, Industry, Nuclear power and reactors, PhysicsInsulator or superconductor? Physicists find graphene is bothhttp://news.mit.edu/2018/graphene-insulator-superconductor-0305
When rotated at a &quot;magic angle,&quot; graphene sheets can form an insulator or a superconductor.Mon, 05 Mar 2018 11:00:00 -0500Jennifer Chu | MIT News Officehttp://news.mit.edu/2018/graphene-insulator-superconductor-0305<p>It’s hard to believe that a single material can be described by as many superlatives as graphene can. Since its discovery in 2004, scientists have found that the lacy, honeycomb-like sheet of carbon atoms — essentially the most microscopic shaving of pencil lead you can imagine — is not just the thinnest material known in the world, but also incredibly light and flexible, hundreds of times stronger than steel, and more electrically conductive than copper.</p>
<p>Now physicists at MIT and Harvard University have found the wonder material can exhibit even more curious electronic properties. In two papers published today in <em>Nature</em>, the team reports it can tune graphene to behave at two electrical extremes: as an insulator, in which electrons are completely blocked from flowing; and as a superconductor, in which electrical current can stream through without resistance.</p>
<p>Researchers in the past, including this team, have been able to synthesize graphene superconductors by placing the material in contact with other superconducting metals — an arrangement that allows graphene to inherit some superconducting behaviors. This time around, the team found a way to make graphene superconduct on its own, demonstrating that superconductivity can be an intrinsic quality in the purely carbon-based material.</p>
<p>The physicists accomplished this by creating a “superlattice” of two graphene sheets stacked together — not precisely on top of each other, but rotated ever so slightly, at a “magic angle” of 1.1 degrees. As a result, the overlaying, hexagonal honeycomb pattern is offset slightly, creating a precise moiré configuration that is predicted to induce strange, “strongly correlated interactions” between the electrons in the graphene sheets. In any other stacked configuration, graphene prefers to remain distinct, interacting very little, electronically or otherwise, with its neighboring layers.</p>
<p>The team, led by Pablo Jarillo-Herrero, an associate professor of physics at MIT, found that when rotated at the magic angle, the two sheets of graphene exhibit nonconducting behavior, similar to an exotic class of materials known as Mott insulators. When the researchers then applied voltage, adding small amounts of electrons to the graphene superlattice, they found that, at a certain level, the electrons broke out of the initial insulating state and flowed without resistance, as if through a superconductor.</p>
<p>“We can now use graphene as a new platform for investigating unconventional superconductivity,” Jarillo-Herrero says. “One can also imagine making a superconducting transistor out of graphene, which you can switch on and off, from superconducting to insulating. That opens many possibilities for quantum devices.”</p>
<p><img alt="" src="/sites/mit.edu.newsoffice/files/magic-angle_0.gif" /></p>
<p><span style="font-size:10px;"><em>A large-scale interpretation of the moiré patterns formed when one graphene lattice is slightly rotated at a “magic angle,” with respect to a second graphene lattice.</em></span></p>
<p><strong>A 30-year gap</strong></p>
<p>A material’s ability to conduct electricity is normally represented in terms of energy bands. A single band represents a range of energies that a material’s electrons can have. There is an energy gap between bands, and when one band is filled, an electron must embody extra energy to overcome this gap, in order to occupy the next empty band.</p>
<p>A material is considered an insulator if the last occupied energy band is completely filled with electrons. Electrical conductors such as metals, on the other hand, exhibit partially filled energy bands, with empty energy states which the electrons can fill to freely move.</p>
<p>Mott insulators, however, are a class of materials that appear from their band structure to conduct electricity, but when measured, they behave as insulators. Specifically, their energy bands are half-filled, but because of strong electrostatic interactions between electrons (such as charges of equal sign repelling each other), the material does not conduct electricity. The half-filled band essentially splits into two miniature, almost-flat bands, with electrons completely occupying one band and leaving the other empty, and hence behaving as an insulator.</p>
<p>“This means all the electrons are blocked, so it’s an insulator because of this strong repulsion between the electrons, so nothing can flow,” Jarillo-Herrero explains. “Why are Mott insulators important? It turns out the parent compound of most high-temperature superconductors is a Mott insulator.”</p>
<p>In other words, scientists have found ways to manipulate the electronic properties of Mott insulators to turn them into superconductors, at relatively high temperatures of about 100 Kelvin. To do this, they chemically “dope” the material with oxygen, the atoms of which attract electrons out of the Mott insulator, leaving more room for remaining electrons to flow. When enough oxygen is added, the insulator morphs into a superconductor. How exactly this transition occurs, Jarillo-Herrero says, has been a 30-year mystery.</p>
<p>“This is a problem that is 30 years and counting, unsolved,” Jarillo-Herrero says. “These high-temperature superconductors have been studied to death, and they have many interesting behaviors. But we don’t know how to explain them.”</p>
<p><strong>A precise rotation</strong></p>
<p>Jarillo-Herrero and his colleagues looked for a simpler platform to study such unconventional physics. In studying the electronic properties in graphene, the team began to play around with simple stacks of graphene sheets. The researchers created two-sheet superlattices by first exfoliating a single flake of graphene from graphite, then carefully picking up half the flake with a glass slide coated with a sticky polymer and an insulating material of boron nitride.</p>
<p>They then rotated the glass slide very slightly and picked up the second half of the graphene flake, adhering it to the first half. In this way, they created a superlattice with an offset pattern that is distinct from graphene’s original honeycomb lattice.</p>
<p>The team repeated this experiment, creating several “devices,” or graphene superlattices, with various angles of rotation, between 0 and 3 degrees. They attached electrodes to each device and measured an electrical current passing through, then plotted the device’s resistance, given the amount of the original current that passed through.</p>
<p>“If you are off in your rotation angle by 0.2 degrees, all the physics is gone,” Jarillo-Herrero says. “No superconductivity or Mott insulator appears. So you have to be very precise with the alignment angle.”</p>
<p>At 1.1 degrees — a rotation that has been predicted to be a “magic angle” — the researchers found the graphene superlattice electronically resembled a flat band structure, similar to a Mott insulator, in which all electrons carry the same energy regardless of their momentum.</p>
<p>“Imagine the momentum for a car is mass times velocity,” Jarillo-Herrero says. “If you’re driving at 30 miles per hour, you have a certain amount of kinetic energy. If you drive at 60 miles per hour, you have much higher energy, and if you crash, you could deform a much bigger object. This thing is saying, no matter if you go 30 or 60 or 100 miles per hour, they would all have the same energy.”</p>
<p><strong>“Current for free”</strong></p>
<p>For electrons, this means that, even if they are occupying a half-filled energy band, one electron does not have any more energy than any other electron, to enable it to move around in that band. Therefore, even though such a half-filled band structure should act like a conductor, it instead behaves as an insulator — and more precisely, a Mott insulator.</p>
<p>This gave the team an idea: What if they could add electrons to these Mott-like superlattices, similar to how scientists doped Mott insulators with oxygen to turn them into superconductors? Would graphene assume superconducting qualities in turn?</p>
<p>To find out, they applied a small gate voltage to the “magic-angle graphene superlattice,” adding small amounts of electrons to the structure. As a result, individual electrons bound together with other electrons in graphene, allowing them to flow where before they could not. Throughout, the researchers continued to measure the electrical resistance of the material, and found that when they added a certain, small amount of electrons, the electrical current flowed without dissipating energy — just like a superconductor.</p>
<p>“You can flow current for free, no energy wasted, and this is showing graphene can be a superconductor,” Jarillo-Herrero says.</p>
<p>Perhaps more importantly, he says the researchers are able to tune graphene to behave as an insulator or a superconductor, and any phase in between, exhibiting all these diverse properties in one single device. This is in contrast to other methods, in which scientists have had to grow and manipulate hundreds of individual crystals, each of which can be made to behave in just one electronic phase.</p>
<p>“Usually, you have to grow different classes of materials to explore each phase,” Jarillo-Herrero says. “We’re doing this <em>in-situ</em>, in one shot, in a purely carbon device. We can explore all those physics in one device electrically, rather than having to make hundreds of devices. It couldn’t get any simpler.”</p>
<p>This research was supported in part by the Gordon and Betty Moore Foundation and ther National Science Foundation.</p>
Physicists at MIT and Harvard University have found that graphene, a lacy, honeycomb-like sheet of carbon atoms, can behave at two electrical extremes: as an insulator, in which electrons are completely blocked from flowing; and as a superconductor, in which electrical current can stream through without resistance. Courtesy of the researchersGraphene, Materials Science and Engineering, Physics, Quantum computing, Research, School of Science, Nanoscience and nanotechnology